Moving Travis helpers out of run_pylint into shared module.

dhermes · dhermes · commit aa36723c4c89 · 2016-10-03T10:57:28.000-07:00
diff --git a/scripts/run_pylint.py b/scripts/run_pylint.py
@@ -31,6 +31,9 @@
 
 from script_utils import LOCAL_BRANCH_ENV
 from script_utils import LOCAL_REMOTE_ENV
+from script_utils import in_travis
+from script_utils import in_travis_pr
+from script_utils import travis_branch
 
 
 IGNORED_DIRECTORIES = [
@@ -146,10 +149,10 @@ def get_files_for_linting(allow_limited=True):
     against for changed files. (This requires ``allow_limited=True``.)
 
     To speed up linting on Travis pull requests against master, we manually
-    set the diff base to origin/master. We don't do this on non-pull requests
-    since origin/master will be equivalent to the currently checked out code.
-    One could potentially use ${TRAVIS_COMMIT_RANGE} to find a diff base but
-    this value is not dependable.
+    set the diff base to the branch the pull request is against. We don't do
+    this on "push" builds since "master" will be the currently checked out
+    code. One could potentially use ${TRAVIS_COMMIT_RANGE} to find a diff base
+    but this value is not dependable.
 
     To allow faster local ``tox`` runs, the local remote and local branch
     environment variables can be set to specify a remote branch to diff
@@ -164,12 +167,12 @@ def get_files_for_linting(allow_limited=True):
               linted.
     """
     diff_base = None
-    if (os.getenv('TRAVIS_BRANCH') == 'master' and
-            os.getenv('TRAVIS_PULL_REQUEST') != 'false'):
-        # In the case of a pull request into master, we want to
-        # diff against HEAD in master.
-        diff_base = 'origin/master'
-    elif os.getenv('TRAVIS') is None:
+    if in_travis():
+        # In the case of a pull request into a branch, we want to
+        # diff against HEAD in that branch.
+        if in_travis_pr():
+            diff_base = travis_branch()
+    else:
         # Only allow specified remote and branch in local dev.
         remote = os.getenv(LOCAL_REMOTE_ENV)
         branch = os.getenv(LOCAL_BRANCH_ENV)
diff --git a/scripts/script_utils.py b/scripts/script_utils.py
@@ -14,6 +14,72 @@
 
 """Common helpers for testing scripts."""
 
+import os
+
 
 LOCAL_REMOTE_ENV = 'GOOGLE_CLOUD_TESTING_REMOTE'
 LOCAL_BRANCH_ENV = 'GOOGLE_CLOUD_TESTING_BRANCH'
+IN_TRAVIS_ENV = 'TRAVIS'
+TRAVIS_PR_ENV = 'TRAVIS_PULL_REQUEST'
+TRAVIS_BRANCH_ENV = 'TRAVIS_BRANCH'
+
+
+def in_travis():
+    """Detect if we are running in Travis.
+
+    .. _Travis env docs: https://docs.travis-ci.com/user/\
+                         environment-variables\
+                         #Default-Environment-Variables
+
+    See `Travis env docs`_.
+
+    :rtype: bool
+    :returns: Flag indicating if we are running on Travis.
+    """
+    return os.getenv(IN_TRAVIS_ENV) == 'true'
+
+
+def in_travis_pr():
+    """Detect if we are running in a pull request on Travis.
+
+    .. _Travis env docs: https://docs.travis-ci.com/user/\
+                         environment-variables\
+                         #Default-Environment-Variables
+
+    See `Travis env docs`_.
+
+    .. note::
+
+        This assumes we already know we are running in Travis.
+
+    :rtype: bool
+    :returns: Flag indicating if we are in a pull request on Travis.
+    """
+    # NOTE: We're a little extra cautious and make sure that the
+    #       PR environment variable is an integer.
+    try:
+        int(os.getenv(TRAVIS_PR_ENV, ''))
+        return True
+    except ValueError:
+        return False
+
+
+def travis_branch():
+    """Get the current branch of the PR.
+
+    .. _Travis env docs: https://docs.travis-ci.com/user/\
+                         environment-variables\
+                         #Default-Environment-Variables
+
+    See `Travis env docs`_.
+
+    .. note::
+
+        This assumes we already know we are running in Travis
+        during a PR.
+
+    :rtype: str
+    :returns: The name of the branch the current pull request is
+              changed against.
+    """
+    return os.getenv(TRAVIS_BRANCH_ENV)
