feat: add --snapshot-ignore-file-extensions argument to support DVC

Author: noahnu

README.md

@@ -141,6 +141,7 @@ These are the cli options exposed to `pytest` by the plugin.
 | `--snapshot-no-colors`         | Disable test results output highlighting. Equivalent to setting the environment variables `ANSI_COLORS_DISABLED` or `NO_COLOR` | Disabled by default if not in terminal.                                                                      |
 | `--snapshot-patch-pycharm-diff`| Override PyCharm's default diffs viewer when looking at snapshot diffs. See [IDE Integrations](#ide-integrations)        | `False`                                                                                                      |
 | `--snapshot-diff-mode` | Configures how diffs are displayed on assertion failure. If working with very large snapshots, disabling the diff can improve performance. | `detailed` |
+| `--snapshot-ignore-file-extensions` | Comma separated list of file extensions to ignore when walking the file tree and discovering used/unused snapshots. | No extensions are ignored by default. |
 
 ### Assertion Options
 
@@ -462,6 +463,22 @@ The generated snapshot:
 }
 ```
 
+#### Ignoring File Extensions (e.g. DVC Integration)
+
+If using a tool such as [DVC](https://dvc.org/) or other tool where you need to ignore files by file extension, you can update your `pytest.ini` like so:
+
+```ini
+[pytest]
+addopts = --snapshot-ignore-file-extensions dvc
+```
+
+A comma separated list is supported, like so:
+
+```ini
+[pytest]
+addopts = --snapshot-ignore-file-extensions dvc,tmp,zip
+```
+
 ### Extending Syrupy
 
 - [Custom defaults](https://github.com/syrupy-project/syrupy/tree/main/tests/examples/test_custom_defaults.py)

src/syrupy/__init__.py

@@ -102,6 +102,12 @@ def pytest_addoption(parser: "pytest.Parser") -> None:
         dest="diff_mode",
         help="Controls how diffs are represented on snapshot assertion failure",
     )
+    group.addoption(
+        "--snapshot-ignore-file-extensions",
+        dest="ignore_file_extensions",
+        help="Comma separated list of file extensions to ignore when discovering snapshots",
+        type=lambda v: v.split(","),
+    )
 
 
 def __terminal_color(config: "pytest.Config") -> "ContextManager[None]":
@@ -143,7 +149,10 @@ def pytest_sessionstart(session: Any) -> None:
     Initialize snapshot session before tests are collected and ran.
     https://docs.pytest.org/en/latest/reference.html#_pytest.hookspec.pytest_sessionstart
     """
-    session.config._syrupy = SnapshotSession(pytest_session=session)
+    session.config._syrupy = SnapshotSession(
+        pytest_session=session,
+        ignore_file_extensions=session.config.option.ignore_file_extensions,
+    )
     global _syrupy
     _syrupy = session.config._syrupy
     session.config._syrupy.start()

src/syrupy/extensions/base.py

@@ -108,13 +108,16 @@ def is_snapshot_location(self, *, location: str) -> bool:
         return location.endswith(self._file_extension)
 
     def discover_snapshots(
-        self, *, test_location: "PyTestLocation"
+        self, *, test_location: "PyTestLocation", ignore_extensions: list[str] | None
     ) -> "SnapshotCollections":
         """
         Returns all snapshot collections in test site
         """
         discovered = SnapshotCollections()
-        for filepath in walk_snapshot_dir(self.dirname(test_location=test_location)):
+        for filepath in walk_snapshot_dir(
+            self.dirname(test_location=test_location),
+            ignore_extensions=ignore_extensions,
+        ):
             if self.is_snapshot_location(location=filepath):
                 snapshot_collection = self._read_snapshot_collection(
                     snapshot_location=filepath

src/syrupy/report.py

@@ -112,7 +112,8 @@ def __post_init__(self) -> None:
                 locations_discovered[test_location].add(extension_class)
                 self.discovered.merge(
                     assertion.extension.discover_snapshots(
-                        test_location=assertion.test_location
+                        test_location=assertion.test_location,
+                        ignore_extensions=assertion.session.ignore_file_extensions,
                     )
                 )
 

src/syrupy/session.py

@@ -53,6 +53,10 @@ class ItemStatus(Enum):
 @dataclass
 class SnapshotSession:
     pytest_session: "pytest.Session"
+
+    # List of file extensions to ignore during discovery/processing
+    ignore_file_extensions: list[str] | None = None
+
     # Snapshot report generated on finish
     report: Optional["SnapshotReport"] = None
     # All the collected test items
@@ -212,7 +216,8 @@ def register_request(self, assertion: "SnapshotAssertion") -> None:
             discovered_extensions = {
                 discovered.location: assertion.extension
                 for discovered in assertion.extension.discover_snapshots(
-                    test_location=assertion.test_location
+                    test_location=assertion.test_location,
+                    ignore_extensions=self.ignore_file_extensions,
                 )
                 if discovered.has_snapshots
             }

src/syrupy/utils.py

@@ -30,9 +30,15 @@ def is_xdist_controller() -> bool:
     return bool(worker_count and int(worker_count) > 0 and not is_xdist_worker())
 
 
-def walk_snapshot_dir(root: str) -> Iterator[str]:
+def walk_snapshot_dir(
+    root: str | Path, *, ignore_extensions: list[str] | None = None
+) -> Iterator[str]:
+    ignore_exts: set[str] = set(ignore_extensions or [])
+
     for filepath in Path(root).rglob("*"):
         if not filepath.name.startswith(".") and filepath.is_file():
+            if filepath.suffixes and filepath.suffixes[-1][1:] in ignore_exts:
+                continue
             yield str(filepath)
 
 

tests/integration/test_snapshot_option_ignore_file_extensions.py

@@ -0,0 +1,27 @@
+from pathlib import Path
+
+
+def test_ignore_file_extensions(testdir):
+    # Generate initial snapshot file
+    testdir.makepyfile(
+        test_file=(
+            """
+            def test_case(snapshot):
+                assert snapshot == "some-value"
+            """
+        ),
+    )
+    result = testdir.runpytest("-v", "--snapshot-update")
+    result.stdout.re_match_lines((r"1 snapshot generated\.",))
+    assert result.ret == 0
+
+    # Duplicate the snapshot file with "dvc" file extension
+    snapshot_file = Path(testdir.tmpdir, "__snapshots__", "test_file.ambr")
+    dvc_file = snapshot_file.with_suffix(".ambr.dvc")
+    dvc_file.write_text(snapshot_file.read_text())
+
+    # Run with ignored file extension
+    result = testdir.runpytest(
+        "-v", "--snapshot-details", "--snapshot-ignore-file-extensions=dvc"
+    )
+    result.stdout.no_re_match_line(r".*1 snapshot unused.*")

tests/syrupy/test_utils.py

@@ -14,7 +14,7 @@ def makefiles(testdir, filetree, root=""):
         filepath = Path(root).joinpath(filename)
         if isinstance(contents, dict):
             testdir.mkdir(filepath)
-            makefiles(testdir, contents, filepath)
+            makefiles(testdir, contents, str(filepath))
         else:
             name, ext = str(filepath.with_name(filepath.stem)), filepath.suffix
             testdir.makefile(ext, **{name: contents})
@@ -50,6 +50,36 @@ def test_walk_dir_skips_non_snapshot_path(testfiles):
     }
 
 
+def test_walk_dir_ignores_ignored_extensions(testdir):
+    filetree = {
+        "file1.txt": "file1",
+        "file2.txt": "file2",
+        "__snapshots__": {
+            "snapfile1.ambr": "",
+            "snapfile1.ambr.dvc": "",
+            "snapfolder": {"snapfile2.svg": "<svg></svg>"},
+        },
+    }
+    makefiles(testdir, filetree)
+
+    discovered_files = {
+        str(Path(p).relative_to(Path.cwd()))
+        for p in walk_snapshot_dir(
+            Path(testdir.tmpdir).joinpath("__snapshots__"), ignore_extensions=["dvc"]
+        )
+    }
+
+    assert discovered_files == {
+        str(Path("__snapshots__").joinpath("snapfile1.ambr")),
+        str(Path("__snapshots__").joinpath("snapfolder", "snapfile2.svg")),
+    }
+
+    assert (
+        str(Path("__snapshots__").joinpath("snapfile1.ambr.dvc"))
+        not in discovered_files
+    )
+
+
 def dummy_member():
     return 123