ci: publish dev builds as nightly prereleases (#2959) (#2963)

.github/workflows/pyinstaller.yml

@@ -4,6 +4,24 @@ on:
   push:
     branches: [main, dev]
 
+# Two builds racing on the same branch could leave the nightly tag pointing at
+# one commit while the .exe attached to the release was built from the other.
+concurrency:
+  group: pyinstaller-${{ github.ref }}
+  cancel-in-progress: true
+
+# Needed by "Move the nightly tag to the built commit" below, which force-updates
+# a ref under refs/tags/.
+permissions:
+  contents: write
+
+env:
+  # Deliberately prefixed. A tag named after the branch it was built from shadows
+  # that branch, and a bare `main` then resolves to the tag in every clone:
+  # `git rev-parse main` warns "refname 'main' is ambiguous" and answers with the
+  # tag, not the branch head.
+  NIGHTLY_TAG: nightly-${{ github.ref_name }}
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -41,6 +59,20 @@ jobs:
         with:
           name: maigret_standalone_win32
 
+      # release-action creates a tag only when it does not exist yet, and GitHub
+      # ignores target_commitish once the tag is there ("Unused if the Git tag
+      # already exists"). So the tag has to be moved here, otherwise it stays
+      # pinned to the first build forever while the attached .exe keeps being
+      # replaced on every push.
+      - name: Move the nightly tag to the built commit
+        if: success()
+        run: |
+          set -euo pipefail
+          git tag --force "$NIGHTLY_TAG" "$GITHUB_SHA"
+          # Tag pushes do not match `on.push.branches`, and pushes authenticated
+          # with GITHUB_TOKEN never start a workflow run, so this cannot recurse.
+          git push --force origin "refs/tags/$NIGHTLY_TAG"
+
       - name: Create New Release and Upload PyInstaller Binary to Release
         if: success()
         uses: ncipollo/release-action@v1.14.0
@@ -48,18 +80,23 @@ jobs:
         with:
           allowUpdates: true
           draft: false
-          prerelease: false
+          # A development build must never outrank a stable release. `prerelease`
+          # keeps it out of /releases/latest, and `makeLatest: false` stops it
+          # from stealing the marker back on the next push to main.
+          prerelease: true
           artifactErrorsFailBuild: true
-          makeLatest: true
+          makeLatest: false
           replacesArtifacts: true
           artifacts: maigret_standalone.exe
           name: Development Windows Release [${{ github.ref_name }}]
-          tag: ${{ github.ref_name }}
+          tag: ${{ env.NIGHTLY_TAG }}
+          commit: ${{ github.sha }}
           body: |
-            This is a development release built from the **${{ github.ref_name }}** branch.
+            This is a development release built from the **${{ github.ref_name }}** branch, at commit ${{ github.sha }}.
+            The `${{ env.NIGHTLY_TAG }}` tag is moved to that commit on every build, so it always matches the binary attached below.
 
-            Take into account that `dev` releases may be unstable.
+            It is **not** a stable release — for that, see [the latest release](https://github.com/soxoj/maigret/releases/latest).
-            Please, use [the development release](https://github.com/soxoj/maigret/releases/tag/main) build from the **main** branch.
+            ${{ github.ref_name == 'dev' && 'The `dev` branch is more experimental than `main`. Unless you need a specific unreleased fix, prefer [the `main` development build](https://github.com/soxoj/maigret/releases/tag/nightly-main).' || '' }}
 
             ## How to run
 

tests/test_workflows.py

@@ -0,0 +1,96 @@
+"""Guards for the release-publishing GitHub Actions workflow.
+
+Regression tests for #2959. The PyInstaller development build used to publish
+itself with ``makeLatest: true`` under a tag named after the branch it was built
+from, which caused three separate problems:
+
+1. the Windows dev build held the repository's "Latest release" marker ahead of
+   every stable release, and stole it back on every push to ``main``;
+2. the tag never moved, so it kept naming the first build while the attached
+   ``.exe`` was replaced on every push;
+3. the tags ``main`` / ``dev`` shadowed the branches of the same name, making a
+   bare ``main`` refname ambiguous in every clone.
+
+These tests read the workflow as data, so they fail if any of the three
+conditions is reintroduced.
+"""
+
+import os
+
+import pytest
+
+yaml = pytest.importorskip("yaml")
+
+WORKFLOW_PATH = os.path.join(
+    os.path.dirname(os.path.dirname(os.path.realpath(__file__))),
+    ".github",
+    "workflows",
+    "pyinstaller.yml",
+)
+
+RELEASE_ACTION = "ncipollo/release-action"
+
+
+@pytest.fixture(scope="module")
+def workflow():
+    with open(WORKFLOW_PATH, encoding="utf-8") as f:
+        return yaml.safe_load(f)
+
+
+@pytest.fixture(scope="module")
+def release_step(workflow):
+    steps = workflow["jobs"]["build"]["steps"]
+    matching = [s for s in steps if RELEASE_ACTION in s.get("uses", "")]
+    assert len(matching) == 1, f"expected exactly one {RELEASE_ACTION} step"
+    return matching[0]
+
+
+def _push_branches(workflow):
+    # PyAML resolves the bare `on` key to the boolean True (YAML 1.1 treats it as
+    # a truthy literal), so accept either spelling.
+    triggers = workflow.get("on", workflow.get(True))
+    return triggers["push"]["branches"]
+
+
+def _resolve(expression, workflow, branch):
+    """Expand the workflow-level env and `github.ref_name` in an expression."""
+    for name, value in (workflow.get("env") or {}).items():
+        expression = expression.replace("${{ env.%s }}" % name, str(value))
+    return expression.replace("${{ github.ref_name }}", branch)
+
+
+def test_dev_build_is_a_prerelease(release_step):
+    # Keeps the build out of /releases/latest and out of the `release: released`
+    # event that publishes to PyPI.
+    assert str(release_step["with"]["prerelease"]).lower() == "true"
+
+
+def test_dev_build_never_claims_the_latest_marker(release_step):
+    assert str(release_step["with"]["makeLatest"]).lower() == "false"
+
+
+def test_release_tag_does_not_shadow_a_branch(workflow, release_step):
+    tag = release_step["with"]["tag"]
+    for branch in _push_branches(workflow):
+        resolved = _resolve(tag, workflow, branch)
+        assert resolved != branch, (
+            f"tag {resolved!r} shadows the {branch!r} branch: a bare "
+            f"{branch!r} refname would resolve to the tag in every clone"
+        )
+        assert resolved, f"tag resolved to an empty string for branch {branch!r}"
+
+
+def test_release_tag_is_moved_to_the_built_commit(workflow, release_step):
+    # release-action only creates a tag when it is missing, and GitHub ignores
+    # target_commitish for an existing tag, so an explicit push is what keeps the
+    # tag in step with the attached binary.
+    tag = release_step["with"]["tag"]
+    scripts = [s["run"] for s in workflow["jobs"]["build"]["steps"] if "run" in s]
+    moves_tag = any(
+        "refs/tags/" in script and "--force" in script for script in scripts
+    )
+    assert moves_tag, (
+        f"no step force-pushes {tag!r}; without it the tag stays pinned to the "
+        "first build while the release keeps getting new binaries"
+    )
+    assert workflow.get("permissions", {}).get("contents") == "write"