[github action] display black result in job summary (#3688)

* send output to $GITHUB_STEP_SUMMARY

* update CHANGES.md

* update CHANGES.md with PR number

* implement PR feedback

* fix pre-commit issues (prettier/trailing whitespace)

CHANGES.md

@@ -45,6 +45,8 @@
 
 <!-- For example, Docker, GitHub Actions, pre-commit, editors -->
 
+- Update GitHub Action to display black output in the job summary (#3688)
+
 ### Documentation
 
 <!-- Major changes to documentation and policies. Small docs changes

action.yml

@@ -33,11 +33,12 @@ branding:
 runs:
   using: composite
   steps:
-    - run: |
+    - name: black
+      run: |
         if [ "$RUNNER_OS" == "Windows" ]; then
-          python $GITHUB_ACTION_PATH/action/main.py
+          python $GITHUB_ACTION_PATH/action/main.py | tee -a $GITHUB_STEP_SUMMARY
         else
-          python3 $GITHUB_ACTION_PATH/action/main.py
+          python3 $GITHUB_ACTION_PATH/action/main.py | tee -a $GITHUB_STEP_SUMMARY
         fi
       env:
         # TODO: Remove once https://github.com/actions/runner/issues/665 is fixed.

action/main.py

@@ -32,7 +32,7 @@
                 describe_name = line[len("describe-name: ") :].rstrip()
                 break
     if not describe_name:
-        print("::error::Failed to detect action version.", flush=True)
+        print("::error::Failed to detect action version.", file=sys.stderr, flush=True)
         sys.exit(1)
     # expected format is one of:
     # - 23.1.0
@@ -53,15 +53,25 @@
 )
 if pip_proc.returncode:
     print(pip_proc.stdout)
-    print("::error::Failed to install Black.", flush=True)
+    print("::error::Failed to install Black.", file=sys.stderr, flush=True)
     sys.exit(pip_proc.returncode)
 
 
 base_cmd = [str(ENV_BIN / "black")]
 if BLACK_ARGS:
     # TODO: remove after a while since this is deprecated in favour of SRC + OPTIONS.
-    proc = run([*base_cmd, *shlex.split(BLACK_ARGS)])
+    proc = run(
+        [*base_cmd, *shlex.split(BLACK_ARGS)],
+        stdout=PIPE,
+        stderr=STDOUT,
+        encoding="utf-8",
+    )
 else:
-    proc = run([*base_cmd, *shlex.split(OPTIONS), *shlex.split(SRC)])
-
+    proc = run(
+        [*base_cmd, *shlex.split(OPTIONS), *shlex.split(SRC)],
+        stdout=PIPE,
+        stderr=STDOUT,
+        encoding="utf-8",
+    )
+print(proc.stdout)
 sys.exit(proc.returncode)