Record most relevant commit hash in sketches report for PRs

Previously, the sketches report's commit_hash key was the hash of GitHub's automatically generated hypothetical merge commit when the workflow was triggered by a pull_request event. Instead, the report should show the hash of the PR's head commit.

Unfortunately, the event data provided by GitHub doesn't give the short hash and I don't know a good way of converting the long hash to short. For consistency, the report will now always contain the long hash.

Author: per1234

compilesketches/compilesketches.py

@@ -949,9 +949,7 @@ def get_sketches_report(self, sketch_report_list):
         Keyword arguments:
         sketch_report_list -- list of reports from each sketch compilation
         """
-        # Get the short hash of the pull request head ref
-        repository = git.Repo(path=os.environ["GITHUB_WORKSPACE"])
-        current_git_ref = repository.git.rev_parse("HEAD", short=True)
+        current_git_ref = get_head_commit_hash()
 
         sketches_report = {
             self.ReportKeys.fqbn: self.fqbn,
@@ -1244,6 +1242,22 @@ def get_archive_root_path(archive_extract_path):
     return archive_root_folder_name
 
 
+def get_head_commit_hash():
+    """Return the head commit's hash."""
+    if os.environ["GITHUB_EVENT_NAME"] == "pull_request":
+        # When the workflow is triggered by a pull_request event, actions/checkout checks out the hypothetical merge
+        # commit GitHub automatically generates for PRs. The user will expect the report to show the hash of the head
+        # commit of the PR, not of this hidden merge commit. So it's necessary it get it from GITHUB_EVENT_PATH instead
+        # of git rev-parse HEAD.
+        with open(file=os.environ["GITHUB_EVENT_PATH"]) as github_event_file:
+            commit_hash = json.load(github_event_file)["pull_request"]["head"]["sha"]
+    else:
+        repository = git.Repo(path=os.environ["GITHUB_WORKSPACE"])
+        commit_hash = repository.git.rev_parse("HEAD")
+
+    return commit_hash
+
+
 # Only execute the following code if the script is run directly, not imported
 if __name__ == "__main__":
     main()

compilesketches/tests/test_compilesketches.py

@@ -1500,18 +1500,9 @@ def test_get_sketches_report(monkeypatch, mocker):
     fqbn_arg = "arduino:avr:uno"
     current_git_ref = "fooref"
 
-    # Stub
-    class Repo:
-        def __init__(self):
-            self.git = self
-
-        def rev_parse(self):
-            pass
-
     monkeypatch.setenv("GITHUB_REPOSITORY", github_repository)
 
-    mocker.patch("git.Repo", autospec=True, return_value=Repo())
-    mocker.patch.object(Repo, "rev_parse", return_value=current_git_ref)
+    mocker.patch("compilesketches.get_head_commit_hash", autospec=True, return_value=current_git_ref)
 
     sizes_summary_report = unittest.mock.sentinel.sizes_summary_report
     sketch_report_list = unittest.mock.sentinel.sketch_report_list
@@ -1533,8 +1524,6 @@ def rev_parse(self):
         compilesketches.CompileSketches.ReportKeys.sketch: sketch_report_list
     }
 
-    git.Repo.assert_called_once_with(path=os.environ["GITHUB_WORKSPACE"])
-    Repo.rev_parse.assert_called_once_with("HEAD", short=True)
     compile_sketches.get_sizes_summary_report.assert_called_once_with(compile_sketches,
                                                                       sketch_report_list=sketch_report_list)
 
@@ -2033,3 +2022,23 @@ def test_clone_repository(tmp_path, git_ref):
     # Verify that the installation matches the test clone
     assert directories_are_same(left_directory=destination_path,
                                 right_directory=test_clone_path)
+
+
+@pytest.mark.parametrize("github_event, expected_hash",
+                         [("pull_request", "pull_request-head-sha"), ("push", "push-head-sha")])
+def test_get_head_commit_hash(monkeypatch, mocker, github_event, expected_hash):
+    # Stub
+    class Repo:
+        def __init__(self):
+            self.git = self
+
+        def rev_parse(self):
+            pass
+
+    monkeypatch.setenv("GITHUB_EVENT_NAME", github_event)
+    monkeypatch.setenv("GITHUB_EVENT_PATH", str(test_data_path.joinpath("githubevent.json")))
+
+    mocker.patch("git.Repo", autospec=True, return_value=Repo())
+    mocker.patch.object(Repo, "rev_parse", return_value="push-head-sha")
+
+    assert compilesketches.get_head_commit_hash() == expected_hash

compilesketches/tests/testdata/githubevent.json

@@ -1,5 +1,8 @@
 {
   "pull_request": {
+    "head": {
+      "sha": "pull_request-head-sha"
+    },
     "number": 42
   }
 }