CONTRIBUTING: document test262.py, async tests

add a section on requirements for using console test runner test262.py

add a section on asynchronous tests

add subsection to authoring guidelines with suggestion for test names

CONTRIBUTING.md

+## Using the Console Test Runner
+
+The console test runner is used to test browserless implementations of ECMAScript, e.g., [v8](http://en.wikipedia.org/wiki/V8_(JavaScript_engine), [node](http://en.wikipedia.org/wiki/Node.js), or [js24](http://packages.ubuntu.com/trusty/libmozjs-24-bin) 
+
+### Requirements
+
+To use the `test262.py` runner, you must have the following:
+
+ * a checkout of the [test262 project](https://github.com/tc39/test262/)
+ * Python 2.7
+ * the Python YAML library [PyYAML](http://www.pyyaml.org)
+ * the javascript engine you intend to test (node, v8, etc.)
+
+### Quick Start
+
+To confirm the console test runner is working on a UNIX-like system
+
+```
+test262$ ./tools/packaging/test262.py --command "node" 7.2_A1.1_T1
+ch07/7.2/S7.2_A1.1_T1 passed in non-strict mode
+
+test262$
+```
+
+On a Windows system:
+
+```
+Z:\test262>tools\packaging\test262.py --command="node" 7.2_A1.1_T1
+ch07\7.2\S7.2_A1.1_T1 passed in non-strict mode
+
+
+Z:\test262>
+```
+
+### Options
+
+Name | Action
+-----|-------
+-h, --help | displays a brief help message
+--command=COMMAND | **required** command which invokes javascript engine to be tested
+--tests=TESTS | path to the test suite; default is current directory
+--cat | don't execute tests, just print code that would be run
+--summary | generate a summary at end of execution
+--full-summary | generate a longer summary with details of test failures
+--strict_only | run only tests that are marked **@onlyStrict**
+--non_strict_only | run only tests that are marked **@noStrict**
+--unmarked_default=MODE | mode to use for tests that are not marked **@onlyStrict** or **@noStrict** ; MODE can be `strict` or `non_strict` or `both`
+--logname=LOGNAME | write output to file (in addition to stdout)
+--junitname=JUNITNAME | write test results to file in JUnit XML format
+--loglevel=LOGLEVEL | set log level, primarily useful for debugging `test262.py` 
+--print-handle=FUNC | enable async test logging via javascript function e.g., `console.log`
+ 
+### Usage Notes
+
+Non-option arguments are used as filters to match test names.  If no filters are found, the whole test suite is run.
+
+Example | Result
+-|-
+test262.py --command="node" | run all tests
+test262.py --command="node" ch07 ch11 | run tests from chapters 7 and 11
+test262.py --command="node" 4.4 | run all tests with "4.4" in the name
+
+The COMMAND argument can be a quoted string.  This is useful when testing ECMAScript6 features in node, because node requires the command-line argument `--harmony` to enable ES6:
+
+```
+$ test262.py --command="node --harmony" es6
+``` 
+
+
 ## Test262 Authoring Guidelines
+
+### Test Case Names
+
+These are guidelines. There is a substantial amount of variation in existing test names.
+
+Test cases are often named by the portion of the spec or draft spec they reference.  A test for ECMAScript 5.1 section [8.7.2 PutValue](http://www.ecma-international.org/ecma-262/5.1/#sec-8.7.2) should be placed in the directory `test262/suite/ch08/8.7/8.7.2/` and have a filename which contains the substring `8.7.2`.  A test for ECMAScript 6.0 draft section [25.4.4.1 Promise.all](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-promise.all) should be placed in directory `test262/suite/es6/ch25/25.4/25.4.4/25.4.4.1` and have a filename that contains the substring `25.4.4.1`.
+
+One common convention is to break down a section into a number of testable assertions (A) and to test each assertion with one or more test cases (T).  For example, section 25.4.4.1 of ES6 could be broken down like this:
+
+ * A1 Promise.all is a function of one argument
+  - A1.1 Promise.all is callable
+  - A1.2 Promise.all expects 1 argument
+ * A2 Promise.all([]) is a Promise immediately resolved with []
+  - A2.1 Promise.all([]) returns a Promise
+  - A2.2 Promise.all([]) is resolved immediately
+  - A2.3 Promise.all([]) is resolved with a new empty array
+
+with test case `S25.4.4.1_A1.1_T1.js` being the first test for assertion A1.1, and `S25.4.4.1_A2.3_T3.js` being the third test for assertion A2.3.
+
 ### Test Case Style
 A test file has the following style format:
 ```javascript
@@ -11,23 +99,30 @@ A test file has the following style format:
  
 [Test Code]
 ```
+
 ### Tags
 Test262 officially supports the following tags: **@description**, **@negative**, **@path** & **@author**
+
 ##### @description
 This tag is used to describe the purpose of a particular testcase. 
 Eg: Insert <LS> between chunks of one string
+
 ##### @negative [.] \(not supported by Python console harness)
 Negative means the test will throw an error and given the error there will be a string comparison on the error message. It has an optional second parameter (it's a *regex-dot* if not provided) that will be used to compare. For best practices on how to use negative tag please see Handling Errors and Negative Test Cases.
+
 ##### @path
-This tag is used by the JSON packaging. It is not needed to manually enter this tag.  
+This tag is used by the JSON packaging. Do not manually enter this tag.  
+
 ##### @author
 This tag is used to identify the author of a test case. It's optional.
 
-There are also couple other tags which are used only by the Python runner: **@onlyStrict**, **@noStrict**
+Some tags which are used only by the Python runner: **@onlyStrict**, **@noStrict**
+
 ##### @onlyStrict
-Will run the test only in strict mode
+Will only run the test in strict mode
+
 ##### @noStrict
-Will not run the test in strict mode
+Will only not run the test in non-strict mode
 
 ### Handling Errors and Negative Test Cases
 The following patterns are considered the best practice:
@@ -64,7 +159,60 @@ The example uses ReferenceError however it's also possible to use any of the fol
 throw "NotEarlyError"; 
 [test code]
 ```
+
 There are *very* few cases where a syntax error is **not** an early error. In those cases use the Runtime Error pattern but wrap the test code in an eval statement. Be careful, eval code is not global code!
+
+### Writing Asynchronous Tests
+
+An asynchronous test is any test that includes the string `$DONE` anywhere in the test file.  The test runner checks for the presence of this string; if it is found, the runner expects that the `$DONE()` function will be called to signal test completion.
+
+ * If the argument to `$DONE` is omitted, is `undefined`, or is any other falsy value, the test is considered to have passed.
+
+ * If the argument to `$DONE` is a truthy value, the test is considered to have failed and the argument is displayed as the failure reason.
+
+A common idiom when writing asynchronous tests is the following:
+
+```js
+var p = new Promise(function () { /* some test code */ });
+
+p.then(function checkAssertions(arg) {
+    if (!expected_condition) {
+      $ERROR("failure message");
+    }
+
+}).then($DONE, $DONE);
+```
+
+Function `checkAssertions` implicitly returns `undefined` if the expected condition is observed.  The return value of function `checkAssertions` is then passed to the first function of the final `then` call, resulting in a call to `$DONE(undefined)`, which signals a passing test.
+
+If the expected condition is not observed, function `checkAssertions` throws a `Test262Error` via function $ERROR.  This is caught by the Promise and passed to the second function in the call -- which is also `$DONE` -- resulting in a call to `$DONE(error_object)`, which signals
+a failing test. 
+
+#### Checking Exception Type and Message in Asynchronous Tests
+
+This idiom can be extended to check for specific exception types or messages:
+
+```js
+p.then(function () {
+    // some code that is expected to throw a TypeError
+
+    return "Expected exception to be thrown";
+}).then($DONE, function (e) {
+   if (!e instanceof TypeError) {
+      $ERROR("Expected TypeError but got " + e);
+   }
+
+   if (!/expected message/.test(e.message)) {
+      $ERROR("Expected message to contain 'expected message' but found " + e.message);
+   }
+
+}).then($DONE, $DONE);
+
+```
+
+
 ### Other Features
+
 #### $INCLUDE(fileName) method
-$INCLUDE (not supported by Python console harness) will load an external Javascript file in the same context before executing a test. In most cases usage of this method should be avoided. It's a good practice only when a large amount of tests need a special check that's not provided by the default harness. If that's the case, please explain the use case in detail.
+
\ No newline at end of file
+$INCLUDE will load an external Javascript file in the same context before executing a test. In most cases usage of this method should be avoided. It's a good practice only when a large amount of tests need a special check that's not provided by the default harness. If that's the case, please explain the use case in detail.