Use a more stable method to detect rosdep changes (#30694)

* Use a more stable method to detect rosdep changes

The method for detecting rosdep changes in the repository checking
system doesn't seem to work very well under all circumstances, and
sometimes fails to determine the differences resulting in a failed job.

This change switches the test to use a line change detection mechanism
already in use in another test, so it should be more stable.

Reverts bdf1c62

* fixup! Use a more stable method to detect rosdep changes

.github/workflows/build_test.yaml

@@ -10,17 +10,14 @@ jobs:
         python-version: [3.8]
     steps:
     - uses: actions/checkout@v2
-      with:
-        fetch-depth: 5
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}
     - name: Fetch upstream (to enable diff)
       run: |
         git remote add unittest_upstream_comparision https://github.com/ros/rosdistro.git || git remote set-url unittest_upstream_comparision https://github.com/ros/rosdistro.git
-        git fetch --no-tags --depth=5 unittest_upstream_comparision master
-        git fetch --no-tags --depth=5 origin $GITHUB_BASE_REF
+        git fetch --no-tags --depth=1 unittest_upstream_comparision master
     - name: Install Dependencies
       run: |
         python -m pip install --upgrade pip setuptools wheel

test/rosdep_repo_check/test_rosdep_repo_check.py

@@ -57,10 +57,25 @@ def detect_lines(diffstr):
 
 
 def get_changed_line_numbers():
-    base_ref = ''
-    GITHUB_BASE_REF = os.environ.get('GITHUB_BASE_REF')
-    if GITHUB_BASE_REF:
-        base_ref = 'remotes/origin/' + GITHUB_BASE_REF + '...'
+    UPSTREAM_NAME = 'unittest_upstream_comparision'
+    DIFF_BRANCH = 'master'
+    DIFF_REPO = 'https://github.com/ros/rosdistro.git'
+
+    # See if UPSTREAM_NAME remote is available and use it as it's expected to be setup by CI
+    # Otherwise fall back to origin/master
+    cmd = 'git config --get remote.%s.url' % UPSTREAM_NAME
+    try:
+        remote_url = subprocess.check_output(cmd.split()).decode('utf-8').strip()
+        # Remote exists
+        # Check url
+        assert remote_url == DIFF_REPO, \
+            '%s remote url [%s] is different than %s' % (UPSTREAM_NAME, remote_url, DIFF_REPO)
+        base_ref = '%s/%s' % (UPSTREAM_NAME, DIFF_BRANCH)
+    except subprocess.CalledProcessError:
+        # No remote so fall back to origin/master
+        print('WARNING: No remote %s detected, falling back to origin master. Make sure it is up to date.' % UPSTREAM_NAME, file=sys.stderr)
+        base_ref = 'origin/master'
+
     cmd = 'git diff --unified=0 %s -- rosdep' % (base_ref,)
     print("Detecting changed rules with '%s'" % (cmd,))
     diff = subprocess.check_output(cmd.split()).decode('utf-8')
@@ -77,6 +92,10 @@ def setUpClass(cls):
         cls._isolated_data = {}
         cls._repo_root = os.path.join(os.path.dirname(__file__), '..', '..')
 
+        # For clarity in the logs, show as 'skipped' rather than 'passed'
+        if not cls._changed_lines:
+            raise unittest.SkipTest('No rosdep changes were detected')
+
         for path in ('rosdep/base.yaml', 'rosdep/python.yaml'):
             if path not in cls._changed_lines:
                 continue