Put the `mojo_test` test list format in the command line description.

mojo/devtools/common/mojo_test

Index: mojo/devtools/common/mojo_test
diff --git a/mojo/devtools/common/mojo_test b/mojo/devtools/common/mojo_test
index 49d00e04ac659cb6ba17c3d280d0df68af17ac37..c824f10b1ae6a5fa5c84002a3498b784aa99b51c 100755
--- a/mojo/devtools/common/mojo_test
+++ b/mojo/devtools/common/mojo_test
@@ -5,8 +5,21 @@
 
 """Test runner for Mojo application tests.
 
-The file describing the list of tests has to be a valid Python program that sets
-a |tests| global variable, containing entries of the following form:
+TODO(vtl|msw): Add a way of specifying data dependencies.

[ppi, 2015/07/29 13:38:43]

here.

+"""
+
+import argparse
+import logging
+import sys
+
+from devtoolslib import apptest_dart
+from devtoolslib import apptest_gtest
+from devtoolslib import shell_arguments
+
+_DESCRIPTION = """Runner for Mojo application tests.
+
+|test_list_file| has to be a valid Python program that sets a |tests| global
+variable, containing entries of the following form:
 
  {
    # Required URL for apptest.
@@ -16,39 +29,28 @@ a |tests| global variable, containing entries of the following form:
    # Optional test type. Valid values:
    #   * "gtest" (default)
    #   * "gtest_isolated": like "gtest", but run with fixture isolation,
-   #      i.e., each test in a fresh mojo_shell)
-   #   * "dart".
+   #      i.e., each test in a fresh mojo_shell
+   #   * "dart"
    "type": "gtest",
-   # Optional arguments for the apptest.
+   # Optional arguments to be passed to the apptest.
    "test-args": ["--an_arg", "another_arg"],
-   # Optional arguments for the shell.
+   # Optional shell arguments.
    "shell-args": ["--some-flag-for-the-shell", "--another-flag"],
  }
 
-The program may use the |target_os| global that will be any of ['android',
-'linux'], indicating the system on which the tests are to be run.
-
-TODO(vtl|msw): Add a way of specifying data dependencies.

[qsr, 2015/07/29 13:37:57]

Where is this todo gone?

-"""
-
-_DESCRIPTION = """Runner for Mojo application tests.
+|test_list_file| may reference the |target_os| global that will be any of
+['android', 'linux'], indicating the system on which the tests are to be run.
 
 Any arguments not recognized by the script will be passed on as shell arguments.
 """
 
-import argparse
-import logging
-import sys
-
-from devtoolslib import apptest_dart
-from devtoolslib import apptest_gtest
-from devtoolslib import shell_arguments
-
 _logger = logging.getLogger()
 
 
 def main():
-  parser = argparse.ArgumentParser(description=_DESCRIPTION)
+  parser = argparse.ArgumentParser(
+      formatter_class=argparse.RawDescriptionHelpFormatter,
+      description=_DESCRIPTION)
   parser.add_argument("test_list_file", type=file,
                       help="a file listing apptests to run")