feat(snapshots): add --snapshot-disable cli option (MODFLOW-USGS#157)

* add --snapshot-disable pytest CLI option to disable snapshot comparisons
* if snapshots are disabled, the snapshot fixture provided to the test function will attest equivalence to anything, e.g. snapshot == "yes, anything" returns True

autotest/conftest.py

@@ -1,4 +1,4 @@
 from pathlib import Path
 
-pytest_plugins = ["modflow_devtools.fixtures"]
+pytest_plugins = ["modflow_devtools.fixtures", "modflow_devtools.snapshots"]
 project_root_path = Path(__file__).parent

autotest/test_snapshots.py

@@ -2,10 +2,11 @@
 from pathlib import Path
 
 import numpy as np
+import pytest
+from _pytest.config import ExitCode
 
 proj_root = Path(__file__).parents[1]
 module_path = Path(inspect.getmodulename(__file__))
-pytest_plugins = ["modflow_devtools.snapshots"]  # activate snapshot fixtures
 snapshot_array = np.array([1.1, 2.2, 3.3])
 snapshots_path = proj_root / "autotest" / "__snapshots__"
 
@@ -61,3 +62,47 @@ def test_readable_text_array_snapshot(readable_array_snapshot):
         ),
         snapshot_array,
     )
+
+
+@pytest.mark.meta("test_snapshot_disable")
+def test_snapshot_disable_inner(snapshot):
+    assert snapshot == "match this!"
+
+
+@pytest.mark.parametrize("disable", [True, False])
+def test_snapshot_disable(disable):
+    inner_fn = test_snapshot_disable_inner.__name__
+    args = [
+        __file__,
+        "-v",
+        "-s",
+        "-k",
+        inner_fn,
+        "-M",
+        "test_snapshot_disable",
+    ]
+    if disable:
+        args.append("--snapshot-disable")
+    assert pytest.main(args) == (ExitCode.OK if disable else ExitCode.TESTS_FAILED)
+
+
+@pytest.mark.meta("test_array_snapshot_disable")
+def test_array_snapshot_disable_inner(array_snapshot):
+    assert array_snapshot == "can you match that?"
+
+
+@pytest.mark.parametrize("disable", [True, False])
+def test_array_snapshot_disable(disable):
+    inner_fn = test_array_snapshot_disable_inner.__name__
+    args = [
+        __file__,
+        "-v",
+        "-s",
+        "-k",
+        inner_fn,
+        "-M",
+        "test_array_snapshot_disable",
+    ]
+    if disable:
+        args.append("--snapshot-disable")
+    assert pytest.main(args) == (ExitCode.OK if disable else ExitCode.TESTS_FAILED)

docs/md/snapshots.md

@@ -14,4 +14,8 @@ To use snapshot fixtures, add the following line to a test file or `conftest.py`
 
 ```python
 pytest_plugins = [ "modflow_devtools.snapshots" ]
-```
+```
+
+## Disable snapshots
+
+Snapshot comparisons can be disabled by invoked `pytest` with the `--snapshot-disable` flag.

modflow_devtools/snapshots.py

@@ -8,10 +8,13 @@
 syrupy = import_optional_dependency("syrupy")
 
 # ruff: noqa: E402
+from syrupy import __import_extension
+from syrupy.assertion import SnapshotAssertion
 from syrupy.extensions.single_file import (
     SingleFileSnapshotExtension,
     WriteMode,
 )
+from syrupy.location import PyTestLocation
 from syrupy.types import (
     PropertyFilter,
     PropertyMatcher,
@@ -90,19 +93,67 @@ def serialize(
         return np.array2string(data, threshold=np.inf)
 
 
+class MatchAnything:
+    def __eq__(self, _):
+        return True
+
+
 # fixtures
 
 
+@pytest.fixture(scope="session")
+def snapshot_disable(pytestconfig) -> bool:
+    return pytestconfig.getoption("--snapshot-disable")
+
+
 @pytest.fixture
-def array_snapshot(snapshot):
-    return snapshot.use_extension(BinaryArrayExtension)
+def snapshot(request, snapshot_disable) -> "SnapshotAssertion":
+    return (
+        MatchAnything()
+        if snapshot_disable
+        else SnapshotAssertion(
+            update_snapshots=request.config.option.update_snapshots,
+            extension_class=__import_extension(request.config.option.default_extension),
+            test_location=PyTestLocation(request.node),
+            session=request.session.config._syrupy,
+        )
+    )
 
 
 @pytest.fixture
-def text_array_snapshot(snapshot):
-    return snapshot.use_extension(TextArrayExtension)
+def array_snapshot(snapshot, snapshot_disable):
+    return (
+        MatchAnything()
+        if snapshot_disable
+        else snapshot.use_extension(BinaryArrayExtension)
+    )
 
 
 @pytest.fixture
-def readable_array_snapshot(snapshot):
-    return snapshot.use_extension(ReadableArrayExtension)
+def text_array_snapshot(snapshot, snapshot_disable):
+    return (
+        MatchAnything()
+        if snapshot_disable
+        else snapshot.use_extension(TextArrayExtension)
+    )
+
+
+@pytest.fixture
+def readable_array_snapshot(snapshot, snapshot_disable):
+    return (
+        MatchAnything()
+        if snapshot_disable
+        else snapshot.use_extension(ReadableArrayExtension)
+    )
+
+
+# pytest config hooks
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--snapshot-disable",
+        action="store_true",
+        default=False,
+        help="Disable snapshot comparisons.",
+    )