Running restricted set of unit tests on Travis PR.

dhermes · dhermes · commit 324a2c389c4f · 2016-10-03T13:43:19.000-07:00
diff --git a/scripts/run_unit_tests.py b/scripts/run_unit_tests.py
@@ -26,6 +26,12 @@
 import subprocess
 import sys
 
+from script_utils import check_output
+from script_utils import get_changed_packages
+from script_utils import in_travis
+from script_utils import in_travis_pr
+from script_utils import travis_branch
+
 
 PROJECT_ROOT = os.path.abspath(
     os.path.join(os.path.dirname(__file__), '..'))
@@ -44,24 +50,6 @@
 UNSET_SENTINEL = object()  # Sentinel for argparser
 
 
-def check_output(*args):
-    """Run a command on the operation system.
-
-    :type args: tuple
-    :param args: Keyword arguments to pass to ``subprocess.check_output``.
-
-    :rtype: str
-    :returns: The raw STDOUT from the command (converted from bytes
-              if necessary).
-    """
-    cmd_output = subprocess.check_output(args)
-    # On Python 3, this returns bytes (from STDOUT), so we
-    # convert to a string.
-    cmd_output = cmd_output.decode('utf-8')
-    # Also strip the output since it usually has a trailing newline.
-    return cmd_output.strip()
-
-
 def get_package_directories():
     """Get a list of directories containing sub-packages.
 
@@ -83,6 +71,30 @@ def get_package_directories():
     return result
 
 
+def get_travis_directories(package_list):
+    """Get list of packages that need to be tested on Travis CI.
+
+    See: https://travis-ci.com/
+
+    If the current Travis build is for a pull request (PR), this will
+    limit the directories to the ones impacted by the PR. Otherwise
+    it will just test all package directories.
+
+    :type package_list: list
+    :param package_list: The list of **all** valid packages with unit tests.
+
+    :rtype: list
+    :returns: A list of all package directories where tests
+              need to be run.
+    """
+    if in_travis_pr():
+        pr_against_branch = travis_branch()
+        return get_changed_packages('HEAD', pr_against_branch,
+                                    package_list)
+    else:
+        return package_list
+
+
 def verify_packages(subset, all_packages):
     """Verify that a subset of packages are among all packages.
 
@@ -107,6 +119,9 @@ def get_test_packages():
     Filters the package list in the following order:
 
     * Check command line for packages passed in as positional arguments
+    * Check if in Travis, then limit the subset based on changes
+      in a Pull Request ("push" builds to branches may not have
+      any filtering)
     * Just use all packages
 
     :rtype: list
@@ -120,6 +135,8 @@ def get_test_packages():
     if args.packages is not UNSET_SENTINEL:
         verify_packages(args.packages, all_packages)
         return sorted(args.packages)
+    elif in_travis():
+        return get_travis_directories(all_packages)
     else:
         return all_packages
 
diff --git a/scripts/script_utils.py b/scripts/script_utils.py
@@ -15,6 +15,7 @@
 """Common helpers for testing scripts."""
 
 import os
+import subprocess
 
 
 LOCAL_REMOTE_ENV = 'GOOGLE_CLOUD_TESTING_REMOTE'
@@ -81,5 +82,80 @@ def travis_branch():
     :rtype: str
     :returns: The name of the branch the current pull request is
               changed against.
+    :raises: :class:`~exceptions.OSError` if the ``TRAVIS_BRANCH_ENV``
+             environment variable isn't set during a pull request
+             build.
     """
-    return os.getenv(TRAVIS_BRANCH_ENV)
+    try:
+        return os.environ[TRAVIS_BRANCH_ENV]
+    except KeyError:
+        msg = ('Pull request build does not have an '
+               'associated branch set (via %s)') % (TRAVIS_BRANCH_ENV,)
+        raise OSError(msg)
+
+
+def check_output(*args):
+    """Run a command on the operation system.
+
+    :type args: tuple
+    :param args: Arguments to pass to ``subprocess.check_output``.
+
+    :rtype: str
+    :returns: The raw STDOUT from the command (converted from bytes
+              if necessary).
+    """
+    cmd_output = subprocess.check_output(args)
+    # On Python 3, this returns bytes (from STDOUT), so we
+    # convert to a string.
+    cmd_output = cmd_output.decode('utf-8')
+    # Also strip the output since it usually has a trailing newline.
+    return cmd_output.strip()
+
+
+def rootname(filename):
+    """Get the root directory that a file is contained in.
+
+    :type filename: str
+    :param filename: The path / name of a file.
+
+    :rtype: str
+    :returns: The root directory containing the file.
+    """
+    if os.path.sep not in filename:
+        return ''
+    else:
+        file_root, _ = filename.split(os.path.sep, 1)
+        return file_root
+
+
+def get_changed_packages(blob_name1, blob_name2, package_list):
+    """Get a list of packages which have changed between two changesets.
+
+    :type blob_name1: str
+    :param blob_name1: The name of a commit hash or branch name or other
+                       ``git`` artifact.
+
+    :type blob_name2: str
+    :param blob_name2: The name of a commit hash or branch name or other
+                       ``git`` artifact.
+
+    :type package_list: list
+    :param package_list: The list of **all** valid packages with unit tests.
+
+    :rtype: list
+    :returns: A list of all package directories that have changed
+              between ``blob_name1`` and ``blob_name2``. Starts
+              with a list of valid packages (``package_list``)
+              and filters out the unchanged directories.
+    """
+    changed_files = check_output(
+        'git', 'diff', '--name-only', blob_name1, blob_name2)
+    changed_files = changed_files.split('\n')
+
+    result = set()
+    for filename in changed_files:
+        file_root = rootname(filename)
+        if file_root in package_list:
+            result.add(file_root)
+
+    return sorted(result)
diff --git a/tox.ini b/tox.ini
@@ -121,6 +121,7 @@ skip_install =
     py34: True
     py35: True
     isolated-cover: True
+passenv = TRAVIS*
 
 [testenv:isolated-cover]
 commands =
