Fix local checkout of cask repo

.github/workflows/tests.yaml

@@ -98,9 +98,14 @@ jobs:
       # https://github.com/pallets/click/issues/2121#issuecomment-1312773882
       # https://gist.github.com/NodeJSmith/e7e37f2d3f162456869f015f842bcf15
       PYTHONIOENCODING: "utf8"
-      # Deactivate Homebrew auto-update and verbose output.
+      # Deactivate Homebrew verbose output and auto-update.
       HOMEBREW_NO_ENV_HINTS: "1"
       HOMEBREW_NO_AUTO_UPDATE: "1"
+      # Do not let brew use its live API to fetch the latest version.
+      # This variable forces brew to use the local repository instead (which we need in destructive tests to checkout
+      # formulas from the past): https://github.com/Homebrew/brew/blob/10845a1/Library/Homebrew/env_config.rb#L314-L317
+      # See: meta_package_manager/tests/test_manager_homebrew.py::TestCask test.
+      HOMEBREW_NO_INSTALL_FROM_API: "1"
     steps:
       - uses: actions/[email protected]
 
@@ -135,6 +140,12 @@ jobs:
         run: |
           brew upgrade
           brew update
+      - name: Homebrew - macOS cask repository copy
+        if: runner.os == 'macOS'
+        # Clone the full copy of the cask repository, so tests on macOS can locally checkout past versions of casks.
+        # This is performed by the destructive meta_package_manager/tests/test_manager_homebrew.py::TestCask test.
+        run: |
+          brew tap homebrew/cask
       - name: Homebrew - Linux install
         if: runner.os == 'Linux'
         run: |

changelog.md

@@ -13,6 +13,7 @@ This version is not released yet and is under active development.
 - \[mpm\] Run bar plugin unittests in their independent, non-parrallel step.
 - \[mpm\] Skip testing on intermediate Python versions to speed up CI. Only the oldest and latest supported.
 - \[mpm\] Skip configuration-related tests while we investigate test isolation.
+- \[mpm\] Fix fetching of full local copy of cask tap in tests to allow for checkout of past formula.
 - \[mpm\] Replace unmaintained `bump2version` by `bump-my-version`.
 
 ## {gh}`5.13.1 (2023-05-04) <compare/v5.13.0...v5.13.1>`

meta_package_manager/tests/test_manager_homebrew.py

@@ -27,13 +27,22 @@
 
 @pytest.fixture()
 def install_cask():
+    """A fixture to install a Cask from a specific commit."""
+
     packages = set()
+    """List of installed packages."""
 
-    def get_cask_path():
+    def get_cask_tap_path():
         """Default location of Homebrew Cask formulas on macOS.
 
-        This is supposed to be a shallow copy of the following Git repository:
-        https://github.com/Homebrew/homebrew-cask
+        This is supposed to be a `shallow copy of the official cask repository
+        <https://github.com/Homebrew/homebrew-cask>`_.
+
+        The later can be obtained with:
+
+        .. code-block:: shell-session
+            $ export HOMEBREW_NO_INSTALL_FROM_API="1"
+            $ brew tap homebrew/cask
         """
         process = subprocess.run(
             ("brew", "--repository"),
@@ -55,9 +64,22 @@ def get_cask_path():
         assert cask_repo.is_dir()
         return cask_repo
 
-    def git_checkout(package_id, commit):
+    def get_cask_folder(package_id: str):
+        """Get the folder where a Cask is located.
+
+        ..warning::
+            As of `aa46114 <https://github.com/Homebrew/homebrew-cask/commit/aa46114>`_,
+            casks have been moved to a subfolder named after their first letter.
+        """
+        cask_folder = get_cask_tap_path().joinpath(package_id[0])
+        assert cask_folder.is_absolute()
+        assert cask_folder.exists()
+        assert cask_folder.is_dir()
+        return cask_folder
+
+    def git_checkout(package_id: str, commit: str):
         process = subprocess.run(
-            ("git", "-C", get_cask_path(), "checkout", commit, f"{package_id}.rb"),
+            ("git", "-C", get_cask_folder(package_id), "checkout", commit, f"{package_id}.rb"),
         )
         assert not process.stderr
         assert process.returncode == 0