check_compliance.py: Avoid running 'git' before _main()

Running 'git rev-parse --show-toplevel' to set GIT_TOP before _main()
prevents any errors from it from being reported to GitHub, because the
GitHub connection hasn't been initialized yet.

If there's an error, the error reporting is currently broken as well,
because git() calls err(), which is defined at the end of the file.

Initialize GIT_TOP in _main() instead of at the top level, and use a
magic "<repo>" string to refer to the top-level repository directory
when setting the 'ComplianceTest.path_hint' class variables instead.

Discovered while working on some unrelated error reporting improvements.

Also move the ZEPHYR_BASE initialization to a better spot, next to other
global variables.

Signed-off-by: Ulf Magnusson <[email protected]>

Author: ulfalizer

scripts/check_compliance.py

@@ -28,6 +28,9 @@
 
 logger = None
 
+# This ends up as None when we're not running in a Zephyr tree
+ZEPHYR_BASE = os.environ.get('ZEPHYR_BASE')
+
 
 def git(*args, cwd=None):
     # Helper for running a Git command. Returns the rstrip()ed stdout output.
@@ -59,13 +62,6 @@ def git(*args, cwd=None):
     return stdout.rstrip()
 
 
-# This ends up as None when we're not running in a Zephyr tree
-ZEPHYR_BASE = os.environ.get('ZEPHYR_BASE')
-
-# The absolute path of the top-level git directory
-GIT_TOP = git("rev-parse", "--show-toplevel")
-
-
 def get_shas(refspec):
     """
     Returns the list of Git SHAs for 'refspec'.
@@ -103,6 +99,12 @@ class ComplianceTest:
     path_hint:
       The path the test runs itself in. This is just informative and used in
       the message that gets printed when running the test.
+
+      The magic string "<git-top>" refers to the top-level repository
+      directory. This avoids running 'git' to find the top-level directory
+      before main() runs (class variable assignments run when the 'class ...'
+      statement runs). That avoids swallowing errors, because main() reports
+      them to GitHub.
     """
     def __init__(self):
         self.case = MyCase(self.name)
@@ -195,7 +197,7 @@ class CheckPatch(ComplianceTest):
     """
     name = "checkpatch"
     doc = "https://docs.zephyrproject.org/latest/contribute/#coding-style"
-    path_hint = GIT_TOP
+    path_hint = "<git-top>"
 
     def run(self):
         # Default to Zephyr's checkpatch if ZEPHYR_BASE is set
@@ -580,7 +582,7 @@ class Codeowners(ComplianceTest):
     """
     name = "Codeowners"
     doc = "https://help.github.com/articles/about-code-owners/"
-    path_hint = GIT_TOP
+    path_hint = "<git-top>"
 
     def ls_owned_files(self, codeowners):
         """Returns an OrderedDict mapping git patterns from the CODEOWNERS file
@@ -712,7 +714,7 @@ class Nits(ComplianceTest):
     """
     name = "Nits"
     doc = "https://docs.zephyrproject.org/latest/contribute/#coding-style"
-    path_hint = GIT_TOP
+    path_hint = "<git-top>"
 
     def run(self):
         # Loop through added/modified files
@@ -823,7 +825,7 @@ class GitLint(ComplianceTest):
     """
     name = "Gitlint"
     doc = "https://docs.zephyrproject.org/latest/contribute/#commit-guidelines"
-    path_hint = GIT_TOP
+    path_hint = "<git-top>"
 
     def run(self):
         # By default gitlint looks for .gitlint configuration only in
@@ -847,7 +849,7 @@ class PyLint(ComplianceTest):
     """
     name = "pylint"
     doc = "https://www.pylint.org/"
-    path_hint = GIT_TOP
+    path_hint = "<git-top>"
 
     def run(self):
         # Path to pylint configuration file
@@ -1012,7 +1014,7 @@ class Identity(ComplianceTest):
     doc = "https://docs.zephyrproject.org/latest/contribute/#commit-guidelines"
     # git rev-list and git log don't depend on the current (sub)directory
     # unless explicited
-    path_hint = GIT_TOP
+    path_hint = "<git-top>"
 
     def run(self):
         for shaidx in get_shas(COMMIT_RANGE):
@@ -1296,6 +1298,11 @@ def _main(args):
     # The "real" main(), which is wrapped to catch exceptions and report them
     # to GitHub. Returns the number of test failures.
 
+    # The absolute path of the top-level git directory. Initialize it here so
+    # that issues running Git can be reported to GitHub.
+    global GIT_TOP
+    GIT_TOP = git("rev-parse", "--show-toplevel")
+
     # The commit range passed in --commit, e.g. "HEAD~3"
     global COMMIT_RANGE
     COMMIT_RANGE = args.commits
@@ -1344,8 +1351,8 @@ def _main(args):
 
         test = testcase()
         try:
-            print("Running {:16} tests in {} ..."
-                  .format(test.name, test.path_hint))
+            print(f"Running {test.name:16} tests in "
+                  f"{GIT_TOP if test.path_hint == '<git-top>' else test.path_hint} ...")
             test.run()
         except EndTest:
             pass