Remove the pytest plugin, recommend inline-snapshot instead (#174)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

Author: samuelcolvin

devtools/pytest_plugin.py

@@ -110,8 +110,7 @@ which is always imported.
 
 ```py
 import sys
-# we don't install here for pytest as it breaks pytest, it is
-# installed later by a pytest fixture
+# importing devtools this early breaks pytest, so skip it there
 if not sys.argv[0].endswith('pytest'):
     import builtins
     try:
@@ -127,3 +126,25 @@ The `ImportError` exception is important since you'll want python to run fine ev
 This approach has another advantage: if you forget to remove `debug(...)` calls from your code, CI
 (which won't have devtools installed) should fail both on execution and linting, meaning you don't end up with
 extraneous debug calls in production code.
+
+## Snapshot testing
+
+Earlier versions of *devtools* shipped a pytest plugin with an `insert_assert()` function which rewrote test files
+to turn a value into an `assert` statement. That plugin has been removed, use
+[inline-snapshot](https://15r10nk.github.io/inline-snapshot/0.36/) instead, which does the same job better and is
+actively maintained.
+
+```py
+from inline_snapshot import snapshot
+
+
+def something():
+    return 1548 * 18489
+
+
+def test_something():
+    assert something() == snapshot()
+```
+
+Running `pytest` with `--inline-snapshot=create` fills in `snapshot()` with the current value, and
+`--inline-snapshot=fix` updates snapshots whose value has changed, after you've checked the new value is right.

docs/usage.md

@@ -48,9 +48,6 @@ Funding = 'https://github.com/sponsors/samuelcolvin'
 Source = 'https://github.com/samuelcolvin/python-devtools'
 Changelog = 'https://github.com/samuelcolvin/python-devtools/releases'
 
-[project.entry-points.pytest11]
-devtools = 'devtools.pytest_plugin'
-
 [tool.uv]
 default-groups = ["dev", "docs"]
 
@@ -60,7 +57,6 @@ module-root = ""
 [dependency-groups]
 dev = [
     "basedpyright>=1.40.2",
-    "black",
     "coverage[toml]",
     "pytest>=8",
     "pytest-mock",

pyproject.toml

@@ -2,8 +2,6 @@
 
 import pytest
 
-pytest_plugins = ['pytester']
-
 
 def pytest_sessionstart(session: pytest.Session) -> None:
     os.environ.pop('PY_DEVTOOLS_HIGHLIGHT', None)