Add -h, --help to swift test and send arguments to -XCTest directly

[aciidgh]

• adds -h and --help to swift test
• passes arguments for running specific tests directly to xctest without adding -XCTest as per proposal

examples:

$ swift test -h
OVERVIEW: Build and run tests

USAGE: swift test [options]

OPTIONS:
  TestModule.TestCase         Run a test case subclass
  TestModule.TestCase/test1   Run a specific test method

$ swift test TestModtest.TestMod/testFoo
Test Suite 'Selected tests' started at 2016-03-03 15:44:05.393
Test Suite 'TestMod' started at 2016-03-03 15:44:05.394
Test Case '-[TestModtest.TestMod testFoo]' started.
testing foo
Test Case '-[TestModtest.TestMod testFoo]' passed (0.001 seconds).
Test Suite 'TestMod' passed at 2016-03-03 15:44:05.395.
     Executed 1 test, with 0 failures (0 unexpected) in 0.001 (0.001) seconds
Test Suite 'Selected tests' passed at 2016-03-03 15:44:05.395.
     Executed 1 test, with 0 failures (0 unexpected) in 0.001 (0.002) seconds

[briancroom]

Very cool!

As a note, I've already started working on a swift-corelibs-xctest branch which adds support for specifying a particular test case to run. At this point I'd think that swift-test should probably just pass extra arguments through unchanged to the test executable on Linux.

[aciidgh]

@briancroom sounds great!
I'd prefer passing the arguments to executable on linux once #160 is merged because it already has the refactoring required in test() method

[mxcl]

Looks good. I am currently waiting on the swift-3-api-guidelines merge before merging anything new.

[aciidgh]

@mxcl can you initiate CI

[mxcl]

@swift-ci Please test

[mxcl]

I fear the OS X one got stuck, but I don’t want to stress our poor CI servers by requesting a new run.

[aciidgh]

This passed CI but got conflicted out pretty badly due to my other PR getting merged. Resolved conflicts and rebased but better to run CI again.

[mxcl]

@swift-ci Please test