diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bd-err.js b/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bd-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..44a9cb1ee857f33f30f6768a65eb099f9f8f84ab
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bd-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the appear adjacent to `0b` | `0B` in a
+  BinaryIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0b_1
diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bd.js b/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bd.js
new file mode 100644
index 0000000000000000000000000000000000000000..f9d5d3cf02099f2009b0f24cef53aa18521f1349
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bd.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0b` | `0B` BinaryDigit NumericLiteralSeparator BinaryDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+---*/
+
+assert.sameValue(0b0_1, 0b01);
+assert.sameValue(0B0_1, 0B01);
diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bds.js b/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bds.js
new file mode 100644
index 0000000000000000000000000000000000000000..26b19114f78e913cb1ff945ed261074540f18092
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-bd-nsl-bds.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0b` | `0B` BinaryDigit NumericLiteralSeparator BinaryDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+---*/
+
+assert.sameValue(0b0_10, 0b010);
+assert.sameValue(0B0_10, 0B010);
diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-bds-nsl-bd.js b/test/language/literals/numeric/numeric-separator-literal-bil-bds-nsl-bd.js
new file mode 100644
index 0000000000000000000000000000000000000000..323259549b15035fec582030731c2c9d1bad8111
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-bds-nsl-bd.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0b` | `0B` BinaryDigits NumericLiteralSeparator BinaryDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+---*/
+
+assert.sameValue(0b01_0, 0b010);
+assert.sameValue(0B01_0, 0B010);
diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-bds-nsl-bds.js b/test/language/literals/numeric/numeric-separator-literal-bil-bds-nsl-bds.js
new file mode 100644
index 0000000000000000000000000000000000000000..744913f05c61ca0ae6ce95d2ca63c1a4772e3439
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-bds-nsl-bds.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0b` | `0B` BinaryDigits NumericLiteralSeparator BinaryDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+---*/
+
+assert.sameValue(0b01_00, 0b0100);
+assert.sameValue(0B01_00, 0B0100);
diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-nsl-bd-dunder-err.js b/test/language/literals/numeric/numeric-separator-literal-bil-nsl-bd-dunder-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..3cadb7a8116c621a850b4259590097a5d4534b3c
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-nsl-bd-dunder-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to another
+  NumericLiteralSeparator in a BinaryIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0b0__0
diff --git a/test/language/literals/numeric/numeric-separator-literal-bil-nsl-bd-err.js b/test/language/literals/numeric/numeric-separator-literal-bil-nsl-bd-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..51ac17e97a18bd681fe6bbc9398762c4389a9539
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-bil-nsl-bd-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character of a
+  BinaryIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  BinaryIntegerLiteral ::
+    0b BinaryDigits
+    0B BinaryDigits
+
+  BinaryDigits ::
+    BinaryDigit
+    BinaryDigits BinaryDigit
+    BinaryDigits NumericLiteralSeparator BinaryDigit
+
+  BinaryDigit :: one of
+    0 1
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0b0_
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-minus-dd-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-minus-dd-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..f7bca1ee7b08ef752004eda258b1e28660b597f9
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-minus-dd-nsl-dd.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  DecimalDigits `.` DecimalDigits ExponentPart_opt `-` DecimalDigits
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  SignedInteger ::
+    ...
+    - DecimalDigits
+    ...
+
+---*/
+
+assert.sameValue(1.0e-1_0, 1.0e-10);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-minus-dds-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-minus-dds-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..9057143c62d57ffa01dff527aad2c95e9ec96411
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-minus-dds-nsl-dd.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  DecimalDigits `.` DecimalDigits ExponentPart_opt `-` DecimalDigits
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  SignedInteger ::
+    ...
+    - DecimalDigits
+    ...
+
+---*/
+
+assert.sameValue(1.0e-10_0, 1.0e-100);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-plus-dd-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-plus-dd-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..ac5b67c2b7d3b02129fe946e07cae57ef302c328
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-plus-dd-nsl-dd.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  DecimalDigits `.` DecimalDigits ExponentPart_opt `+` DecimalDigits
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  SignedInteger ::
+    ...
+    + DecimalDigits
+    ...
+
+---*/
+
+assert.sameValue(1.0e+1_0, 1.0e+10);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-plus-dds-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-plus-dds-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..eeeb5f957eb707fb296acacdef6feb6640f21071
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-dot-dd-ep-sign-plus-dds-nsl-dd.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  DecimalDigits `.` DecimalDigits ExponentPart_opt `+` DecimalDigits
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  SignedInteger ::
+    ...
+    + DecimalDigits
+    ...
+
+---*/
+
+assert.sameValue(1.0e+10_0, 1.0e+100);
+
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-nsl-dd-one-of.js b/test/language/literals/numeric/numeric-separator-literal-dd-nsl-dd-one-of.js
new file mode 100644
index 0000000000000000000000000000000000000000..79f5b5ada08c17af9b1a3843bff2e512be40e939
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-nsl-dd-one-of.js
@@ -0,0 +1,34 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: NonZeroDigit NumericLiteralSeparator DecimalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+
+  DecimalDigits ::
+    DecimalDigit
+    ...
+
+  DecimalDigit :: one of
+    0 1 2 3 4 5 6 7 8 9
+
+---*/
+
+assert.sameValue(1_0, 10);
+assert.sameValue(1_1, 11);
+assert.sameValue(1_2, 12);
+assert.sameValue(1_3, 13);
+assert.sameValue(1_4, 14);
+assert.sameValue(1_5, 15);
+assert.sameValue(1_6, 16);
+assert.sameValue(1_7, 17);
+assert.sameValue(1_8, 18);
+assert.sameValue(1_9, 19);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-nsl-dds-dunder-err.js b/test/language/literals/numeric/numeric-separator-literal-dd-nsl-dds-dunder-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..800714be2c097cf64db3052672b99759aa578f2f
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-nsl-dds-dunder-err.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to another
+  NumericLiteralSeparator in a DecimalIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+1__0123456789
diff --git a/test/language/literals/numeric/numeric-separator-literal-dd-nsl-err.js b/test/language/literals/numeric/numeric-separator-literal-dd-nsl-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..11b89ce2c67b012fe1d05094b255a69d0a655ec0
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dd-nsl-err.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+1_
diff --git a/test/language/literals/numeric/numeric-separator-literal-dds-dot-dd-nsl-dd-ep-dd.js b/test/language/literals/numeric/numeric-separator-literal-dds-dot-dd-nsl-dd-ep-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..a3f78d5060e086b84ab5159125acd3678f05d640
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dds-dot-dd-nsl-dd-ep-dd.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  DecimalDigits `.` DecimalDigits NumericLiteralSeparator DecimalDigits
+  ExponentPart SignedInteger
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+---*/
+
+assert.sameValue(10.00_01e2, 10.0001e2);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dds-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-dds-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..3ca1dee1e3d391effcd3585be704e3b81baf2541
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dds-nsl-dd.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: DecimalDigits NumericLiteralSeparator DecimalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+---*/
+
+assert.sameValue(123456789_0, 1234567890);
+assert.sameValue(123456789_1, 1234567891);
+assert.sameValue(123456789_2, 1234567892);
+assert.sameValue(123456789_3, 1234567893);
+assert.sameValue(123456789_4, 1234567894);
+assert.sameValue(123456789_5, 1234567895);
+assert.sameValue(123456789_6, 1234567896);
+assert.sameValue(123456789_7, 1234567897);
+assert.sameValue(123456789_8, 1234567898);
+assert.sameValue(123456789_9, 1234567899);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dds-nsl-dds-dunder-err.js b/test/language/literals/numeric/numeric-separator-literal-dds-nsl-dds-dunder-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..560fe23576b2ba4ecf3ad420100ed7e7973d2c35
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dds-nsl-dds-dunder-err.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to another
+  NumericLiteralSeparator in DecimalIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+10__0123456789
diff --git a/test/language/literals/numeric/numeric-separator-literal-dds-nsl-err.js b/test/language/literals/numeric/numeric-separator-literal-dds-nsl-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..a72b521e73a9d0047b2d7bf1b8932cc441ae4ffd
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dds-nsl-err.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character of a
+  DecimalLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+10_
diff --git a/test/language/literals/numeric/numeric-separator-literal-dil-dot-dds-nsl-ep-dd-err.js b/test/language/literals/numeric/numeric-separator-literal-dil-dot-dds-nsl-ep-dd-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..ce96ca079b2d2e1ab8e6c7b9527241984b8be4dc
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dil-dot-dds-nsl-ep-dd-err.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+10.0_e1
diff --git a/test/language/literals/numeric/numeric-separator-literal-dil-dot-nsl-ep-err.js b/test/language/literals/numeric/numeric-separator-literal-dil-dot-nsl-ep-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..9b2c418bef459e467372b6de5d8db09c219a36ba
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dil-dot-nsl-ep-err.js
@@ -0,0 +1,29 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear between `.` and ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+   e E
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+10._e1
diff --git a/test/language/literals/numeric/numeric-separator-literal-dil-dot-nsl-err.js b/test/language/literals/numeric/numeric-separator-literal-dil-dot-nsl-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..6d7542eb79328389ff7d83ad8b5991c638d3a190
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dil-dot-nsl-err.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character of a
+  DecimalLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    DecimalIntegerLiteral . DecimalDigits_opt ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+10._
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-dd-nsl-dd-ep.js b/test/language/literals/numeric/numeric-separator-literal-dot-dd-nsl-dd-ep.js
new file mode 100644
index 0000000000000000000000000000000000000000..26cf232cf99e141c58c5e485fe41f95acf054151
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-dd-nsl-dd-ep.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `.` DecimalDigit NumericLiteralSeparator DecimalDigit ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    DecimalDigit
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+---*/
+
+assert.sameValue(.0_1e2, .01e2);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-dd-nsl-dds-ep.js b/test/language/literals/numeric/numeric-separator-literal-dot-dd-nsl-dds-ep.js
new file mode 100644
index 0000000000000000000000000000000000000000..0ded986ab66fdd7c9a240e93a8664414f4f23560
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-dd-nsl-dds-ep.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `.` DecimalDigit NumericLiteralSeparator DecimalDigits ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    DecimalDigit
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+---*/
+
+assert.sameValue(.1_01e2, .101e2);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-dd-ep.js b/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-dd-ep.js
new file mode 100644
index 0000000000000000000000000000000000000000..e3acbad8a23e2e9e63a8aff074b6655601f88245
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-dd-ep.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `.` DecimalDigits NumericLiteralSeparator DecimalDigit ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    DecimalDigit
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+---*/
+
+assert.sameValue(.10_1e2, .101e2);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-dds-ep.js b/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-dds-ep.js
new file mode 100644
index 0000000000000000000000000000000000000000..c437ef997c65e65b1e000fda2871a0115d991f3c
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-dds-ep.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `.` DecimalDigits NumericLiteralSeparator DecimalDigits ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    DecimalDigit
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+---*/
+
+assert.sameValue(.00_01e2, .0001e2);
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-ep-err.js b/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-ep-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..f968e63d6c1635b0d9b70bb846c8fd72417b39a6
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-dds-nsl-ep-err.js
@@ -0,0 +1,28 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: NumericLiteralSeparator may not appear adjacent to ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+.0_e1
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-nsl-ep-err.js b/test/language/literals/numeric/numeric-separator-literal-dot-nsl-ep-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..df26f129d56cdd58c56cd58148f35826ef6d3142
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-nsl-ep-err.js
@@ -0,0 +1,29 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear between `.` and ExponentPart
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+  ExponentIndicator :: one of
+    e E
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+._e1
diff --git a/test/language/literals/numeric/numeric-separator-literal-dot-nsl-err.js b/test/language/literals/numeric/numeric-separator-literal-dot-nsl-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..322dcbf8ee62079cd4b514fb36d92aa55761b623
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-dot-nsl-err.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character of a
+  DecimalLiteral, nor adjacent to `.`
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalLiteral ::
+    . DecimalDigits ExponentPart_opt
+
+  DecimalDigits ::
+    ...
+    DecimalDigits NumericLiteralSeparator DecimalDigit
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+._
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hd-err.js b/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hd-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..d4f73eed20f78215a98d2527122040f9aa7f78e2
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hd-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the appear adjacent to `0x` | `0X` in a
+  HexIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0x_1
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hd.js b/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hd.js
new file mode 100644
index 0000000000000000000000000000000000000000..f8a33c65f45e93ff7396fd66a9ff671213e24e05
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hd.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0x` | `0X` HexDigit NumericLiteralSeparator HexDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+---*/
+
+assert.sameValue(0x0_1, 0x01);
+assert.sameValue(0X0_1, 0X01);
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hds.js b/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hds.js
new file mode 100644
index 0000000000000000000000000000000000000000..0561c9ad95dbbafda73f4a4eac9e88db74b15b03
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-hd-nsl-hds.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0x` | `0X` HexDigit NumericLiteralSeparator HexDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+---*/
+
+assert.sameValue(0x0_10, 0x010);
+assert.sameValue(0X0_10, 0X010);
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-hds-nsl-hd.js b/test/language/literals/numeric/numeric-separator-literal-hil-hds-nsl-hd.js
new file mode 100644
index 0000000000000000000000000000000000000000..6dff72fa38b762873522f017947dd8494c795c4a
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-hds-nsl-hd.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0x` | `0X` HexDigits NumericLiteralSeparator HexDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+---*/
+
+assert.sameValue(0x01_0, 0x010);
+assert.sameValue(0X01_0, 0X010);
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-hds-nsl-hds.js b/test/language/literals/numeric/numeric-separator-literal-hil-hds-nsl-hds.js
new file mode 100644
index 0000000000000000000000000000000000000000..2672484cbca266b21d875f742ef0ba87aad4c68e
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-hds-nsl-hds.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0x` | `0X` HexDigits NumericLiteralSeparator HexDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+---*/
+
+assert.sameValue(0x01_00, 0x0100);
+assert.sameValue(0X01_00, 0X0100);
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-nsl-hd-dunder-err.js b/test/language/literals/numeric/numeric-separator-literal-hil-nsl-hd-dunder-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..dcf0f40a37d131f9fa24af284e3b8703da3e45e0
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-nsl-hd-dunder-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to another
+  NumericLiteralSeparator in a HexIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0x0__0
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-nsl-hd-err.js b/test/language/literals/numeric/numeric-separator-literal-hil-nsl-hd-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..7205cbb2198989b501acc235f128ef2881ce2728
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-nsl-hd-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character of a
+  HexIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0x0_
diff --git a/test/language/literals/numeric/numeric-separator-literal-hil-od-nsl-od-one-of.js b/test/language/literals/numeric/numeric-separator-literal-hil-od-nsl-od-one-of.js
new file mode 100644
index 0000000000000000000000000000000000000000..3f81986dd5d99f4dcbac4169f2d63679fbd46aee
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-hil-od-nsl-od-one-of.js
@@ -0,0 +1,47 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0x` | `0X` HexDigit NumericLiteralSeparator HexDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  HexIntegerLiteral ::
+    0x HexDigits
+    0X HexDigits
+
+  HexDigits ::
+    HexDigit
+    HexDigits HexDigit
+    HexDigits NumericLiteralSeparator HexDigit
+
+  HexDigit::one of
+    0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
+
+---*/
+
+assert.sameValue(0x0_0, 0x00);
+assert.sameValue(0x1_1, 0x11);
+assert.sameValue(0x2_2, 0x22);
+assert.sameValue(0x3_3, 0x33);
+assert.sameValue(0x4_4, 0x44);
+assert.sameValue(0x5_5, 0x55);
+assert.sameValue(0x6_6, 0x66);
+assert.sameValue(0x7_7, 0x77);
+assert.sameValue(0x8_8, 0x88);
+assert.sameValue(0x9_9, 0x99);
+assert.sameValue(0xa_a, 0xaa);
+assert.sameValue(0xb_b, 0xbb);
+assert.sameValue(0xc_c, 0xcc);
+assert.sameValue(0xd_d, 0xdd);
+assert.sameValue(0xe_e, 0xee);
+assert.sameValue(0xf_f, 0xff);
+assert.sameValue(0xA_A, 0xAA);
+assert.sameValue(0xB_B, 0xBB);
+assert.sameValue(0xC_C, 0xCC);
+assert.sameValue(0xD_D, 0xDD);
+assert.sameValue(0xE_E, 0xEE);
+assert.sameValue(0xF_F, 0xFF);
diff --git a/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dd-one-of.js b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dd-one-of.js
new file mode 100644
index 0000000000000000000000000000000000000000..528546e4b1c0705e0a47ac2ee26386687f68b46f
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dd-one-of.js
@@ -0,0 +1,38 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: NonZeroDigit NumericLiteralSeparator DecimalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+  NonZeroDigit :: one of
+    1 2 3 4 5 6 7 8 9
+
+  DecimalDigits ::
+    DecimalDigit
+    ...
+
+  DecimalDigit :: one of
+    0 1 2 3 4 5 6 7 8 9
+
+---*/
+
+assert.sameValue(1_0, 10);
+assert.sameValue(1_1, 11);
+assert.sameValue(2_2, 22);
+assert.sameValue(3_3, 33);
+assert.sameValue(4_4, 44);
+assert.sameValue(5_5, 55);
+assert.sameValue(6_6, 66);
+assert.sameValue(7_7, 77);
+assert.sameValue(8_8, 88);
+assert.sameValue(9_9, 99);
+
+
diff --git a/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..3f6e166a838edee8407fa9eaca9132de1e458f9c
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dd.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: NonZeroDigit NumericLiteralSeparator DecimalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+  NonZeroDigit :: one of
+    1 2 3 4 5 6 7 8 9
+
+  DecimalDigits ::
+    ...
+    DecimalDigits DecimalDigit
+    ...
+
+---*/
+
+assert.sameValue(1_1, 11);
diff --git a/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds-dunder-err.js b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds-dunder-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..dd2f133fa084a9889db9d80ca78f966da2769f1e
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds-dunder-err.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to another
+  NumericLiteralSeparator in DecimalIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+  NonZeroDigit :: one of
+    1 2 3 4 5 6 7 8 9
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0__0123456789
diff --git a/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds-leading-zero-err.js b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds-leading-zero-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..201ac0acdf082e688b90f8ae76f82af8cfecbe2e
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds-leading-zero-err.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: NonZeroDigit NumericLiteralSeparator DecimalDigits
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator DecimalDigits
+
+  NonZeroDigit :: one of
+    1 2 3 4 5 6 7 8 9
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0_0123456789
diff --git a/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds.js b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds.js
new file mode 100644
index 0000000000000000000000000000000000000000..47ea301dace17a4346378360b533ebd361059a7d
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-nzd-nsl-dds.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: NonZeroDigit NumericLiteralSeparator DecimalDigits
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  DecimalIntegerLiteral ::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+  NonZeroDigit :: one of
+    1 2 3 4 5 6 7 8 9
+
+  DecimalDigits ::
+    ...
+    DecimalDigits DecimalDigit
+    ...
+
+---*/
+
+assert.sameValue(1_0123456789, 10123456789);
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-nsl-od-dunder-err.js b/test/language/literals/numeric/numeric-separator-literal-oil-nsl-od-dunder-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..9be6a2b73fc12bf15c2e14d90efe414d5dfa3418
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-nsl-od-dunder-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not appear adjacent to another
+  NumericLiteralSeparator in a OctalIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0o0__0
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-nsl-od-err.js b/test/language/literals/numeric/numeric-separator-literal-oil-nsl-od-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..1d8b21e8399be5b351880d379e284c18e6b011af
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-nsl-od-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the last digit character of an
+  OctalIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0o0_
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od-err.js b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..34276984f853640c616a3b18fb25552c17746d27
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od-err.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NumericLiteralSeparator may not be the appear adjacent to `0o` | `0O` in a
+  OctalIntegerLiteral
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+0o_1
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od-one-of.js b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od-one-of.js
new file mode 100644
index 0000000000000000000000000000000000000000..f9d0f6b16f416a14c9d0d1f529e79cbea36f5bb1
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od-one-of.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0o` | `0O` OctalDigit NumericLiteralSeparator OctalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+---*/
+
+assert.sameValue(0o0_0, 0o00);
+assert.sameValue(0o1_1, 0o11);
+assert.sameValue(0o2_2, 0o22);
+assert.sameValue(0o3_3, 0o33);
+assert.sameValue(0o4_4, 0o44);
+assert.sameValue(0o5_5, 0o55);
+assert.sameValue(0o6_6, 0o66);
+assert.sameValue(0o7_7, 0o77);
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od.js b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od.js
new file mode 100644
index 0000000000000000000000000000000000000000..8555afc406e1e9fce27aef8cb36ccda44a3f532f
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-od.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0o` | `0O` OctalDigit NumericLiteralSeparator OctalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+---*/
+
+assert.sameValue(0o0_1, 0o01);
+assert.sameValue(0O0_1, 0O01);
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-ods.js b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-ods.js
new file mode 100644
index 0000000000000000000000000000000000000000..70bc8396dabe0c81d3ebcfd62f48a31539cc2398
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-od-nsl-ods.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0o` | `0O` OctalDigit NumericLiteralSeparator OctalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+---*/
+
+assert.sameValue(0o0_10, 0o010);
+assert.sameValue(0O0_10, 0O010);
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-ods-nsl-od.js b/test/language/literals/numeric/numeric-separator-literal-oil-ods-nsl-od.js
new file mode 100644
index 0000000000000000000000000000000000000000..7083418e11e4e4182b4716d7fd6532fed228993f
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-ods-nsl-od.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0o` | `0O` OctalDigits NumericLiteralSeparator OctalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+---*/
+
+assert.sameValue(0o01_0, 0o010);
+assert.sameValue(0O01_0, 0O010);
diff --git a/test/language/literals/numeric/numeric-separator-literal-oil-ods-nsl-ods.js b/test/language/literals/numeric/numeric-separator-literal-oil-ods-nsl-ods.js
new file mode 100644
index 0000000000000000000000000000000000000000..2e33e076f77c28899025d582258630f6b515855b
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-oil-ods-nsl-ods.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  `0o` | `0O` OctalDigits NumericLiteralSeparator OctalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  OctalIntegerLiteral ::
+    0o OctalDigits
+    0O OctalDigits
+
+  OctalDigits ::
+    OctalDigit
+    OctalDigits OctalDigit
+    OctalDigits NumericLiteralSeparator OctalDigit
+
+  OctalDigit :: one of
+    0 1 2 3 4 5 6 7
+
+---*/
+
+assert.sameValue(0o01_00, 0o0100);
+assert.sameValue(0O01_00, 0O0100);
diff --git a/test/language/literals/numeric/numeric-separator-literal-sign-minus-dds-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-sign-minus-dds-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..e11952a61f15ccb82d533e88d46f1b60ad720701
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-sign-minus-dds-nsl-dd.js
@@ -0,0 +1,26 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: DecimalDigits NumericLiteralSeparator DecimalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  SignedInteger ::
+    ...
+    - DecimalDigits
+
+---*/
+
+assert.sameValue(-123456789_0, -1234567890);
+assert.sameValue(-123456789_1, -1234567891);
+assert.sameValue(-123456789_2, -1234567892);
+assert.sameValue(-123456789_3, -1234567893);
+assert.sameValue(-123456789_4, -1234567894);
+assert.sameValue(-123456789_5, -1234567895);
+assert.sameValue(-123456789_6, -1234567896);
+assert.sameValue(-123456789_7, -1234567897);
+assert.sameValue(-123456789_8, -1234567898);
+assert.sameValue(-123456789_9, -1234567899);
diff --git a/test/language/literals/numeric/numeric-separator-literal-sign-plus-dds-nsl-dd.js b/test/language/literals/numeric/numeric-separator-literal-sign-plus-dds-nsl-dd.js
new file mode 100644
index 0000000000000000000000000000000000000000..89050f1a45c2a3ba2d20eb5f460715f3029e5b95
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-sign-plus-dds-nsl-dd.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: DecimalDigits NumericLiteralSeparator DecimalDigit
+info: |
+  NumericLiteralSeparator ::
+    _
+
+  SignedInteger ::
+    ...
+    + DecimalDigits
+    ...
+
+---*/
+
+assert.sameValue(+123456789_0, 1234567890);
+assert.sameValue(+123456789_1, 1234567891);
+assert.sameValue(+123456789_2, 1234567892);
+assert.sameValue(+123456789_3, 1234567893);
+assert.sameValue(+123456789_4, 1234567894);
+assert.sameValue(+123456789_5, 1234567895);
+assert.sameValue(+123456789_6, 1234567896);
+assert.sameValue(+123456789_7, 1234567897);
+assert.sameValue(+123456789_8, 1234567898);
+assert.sameValue(+123456789_9, 1234567899);
diff --git a/test/language/literals/numeric/numeric-separator-literal-unicode-err.js b/test/language/literals/numeric/numeric-separator-literal-unicode-err.js
new file mode 100644
index 0000000000000000000000000000000000000000..4674392f36aa081822fdd1039bdb563fa7d36c7e
--- /dev/null
+++ b/test/language/literals/numeric/numeric-separator-literal-unicode-err.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: prod-NumericLiteralSeparator
+description: >
+  NonZeroDigit NumericLiteralSeparator DecimalDigits sequence expressed with
+  unicode escape sequence
+info: |
+  NumericLiteralSeparator::
+    _
+
+  DecimalIntegerLiteral::
+    ...
+    NonZeroDigit NumericLiteralSeparator_opt DecimalDigits
+
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+1\u005F0123456789