chore: remove mutation testing setup

.github/workflows/ci.yml

@@ -205,16 +205,16 @@ jobs:
               run: |
                   pytest posthog/test/mcp --verbose --timeout=30
 
-    mutation-tests:
-        name: Targeted mutation tests
+    utils-quality:
+        name: Utils quality
         runs-on: ubuntu-latest
 
         steps:
             - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
               with:
                   fetch-depth: 0
 
-            - name: Check targeted mutation inputs changed
+            - name: Check utils quality inputs changed
               id: changes
               shell: bash
               run: |
@@ -235,11 +235,11 @@ jobs:
 
                   if [[ -n "$changed_files" ]]; then
                       echo "changed=true" >> "$GITHUB_OUTPUT"
-                      echo "Targeted mutation inputs changed:"
+                      echo "Utils quality inputs changed:"
                       echo "$changed_files"
                   else
                       echo "changed=false" >> "$GITHUB_OUTPUT"
-                      echo "Skipping targeted mutation tests: inputs unchanged."
+                      echo "Skipping utils quality check: inputs unchanged."
                   fi
 
             - name: Set up Python 3.11
@@ -263,33 +263,6 @@ jobs:
                   UV_PROJECT_ENVIRONMENT=$pythonLocation uv run --extra test --with pytest-crap --with pytest-cov pytest posthog/test/test_utils.py posthog/test/test_size_limited_dict.py --timeout=30 --cov=posthog.utils --crap --crap-threshold=10 --crap-top-n=40 -q
                   UV_PROJECT_ENVIRONMENT=$pythonLocation uv run --extra test --with pytest-crap --with pytest-cov python .github/scripts/check_crap_threshold.py posthog/utils.py --max-crap 10
 
-            - name: Restore mutmut cache
-              id: mutmut-cache
-              if: steps.changes.outputs.changed == 'true'
-              uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
-              with:
-                  path: mutants
-                  key: mutmut-${{ runner.os }}-py311-${{ hashFiles('posthog/utils.py', 'posthog/test/test_utils.py', 'posthog/test/test_size_limited_dict.py') }}
-                  restore-keys: |
-                      mutmut-${{ runner.os }}-py311-
-
-            - name: Skip mutation tests on exact cache hit
-              if: steps.changes.outputs.changed == 'true' && steps.mutmut-cache.outputs.cache-hit == 'true'
-              run: |
-                  echo "Skipping targeted mutation tests: exact mutmut cache hit."
-
-            - name: Run targeted mutation tests
-              if: steps.changes.outputs.changed == 'true' && steps.mutmut-cache.outputs.cache-hit != 'true'
-              shell: bash
-              run: |
-                  set -euo pipefail
-                  UV_PROJECT_ENVIRONMENT=$pythonLocation uv run --extra test --with mutmut mutmut run --max-children 1
-                  results="$(UV_PROJECT_ENVIRONMENT=$pythonLocation uv run --extra test --with mutmut mutmut results)"
-                  if [[ -n "$results" ]]; then
-                      echo "$results"
-                      exit 1
-                  fi
-
     import-check:
         name: Python ${{ matrix.python-version }} import check
         runs-on: ubuntu-latest

.gitignore

@@ -22,4 +22,3 @@ pyrightconfig.json
 .DS_Store
 posthog-python-references.json
 .claude/settings.local.json
-mutants/

posthog/utils.py

@@ -21,7 +21,7 @@
 
 def is_naive(dt: datetime) -> bool:
     """Determines if a given datetime.datetime is naive."""
-    return dt.tzinfo is None or dt.tzinfo.utcoffset(dt) is None  # pragma: no mutate
+    return dt.tzinfo is None or dt.tzinfo.utcoffset(dt) is None
 
 
 def total_seconds(delta: timedelta) -> float:
@@ -36,14 +36,12 @@ def guess_timezone(dt: datetime) -> datetime:
         # attempts to guess the datetime.datetime.now() local timezone
         # case, and then defaults to utc
         delta = total_seconds(datetime.now() - dt)
-        if 0 <= delta < 5:  # pragma: no mutate
+        if 0 <= delta < 5:
             # this was created using datetime.datetime.now(),
             # so use the current system local timezone
             # Equivalent to converting the naive value directly because this path
             # only handles values created in the current local timezone.
-            dt = dt.replace(
-                tzinfo=datetime.now().astimezone().tzinfo
-            )  # pragma: no mutate
+            dt = dt.replace(tzinfo=datetime.now().astimezone().tzinfo)
         else:
             # at this point, the best we can do is guess UTC
             dt = dt.replace(tzinfo=timezone.utc)
@@ -62,7 +60,7 @@ def _normalize_timestamp(timestamp: Union[datetime, str]) -> str:
         try:
             # Python 3.10 needs the replacements; on 3.11+ fromisoformat accepts Z
             # and compact UTC offsets such as +0530.
-            normalized_timestamp = timestamp.replace("Z", "+00:00")  # pragma: no mutate
+            normalized_timestamp = timestamp.replace("Z", "+00:00")
             normalized_timestamp = re.sub(
                 r"([+-]\d{2})(\d{2})$", r"\1:\2", normalized_timestamp
             )
@@ -162,7 +160,7 @@ def _coerce_unicode(cmplx: Any) -> Optional[str]:
     item = None
     try:
         if isinstance(cmplx, bytes):
-            item = cmplx.decode("utf-8", "strict")  # pragma: no mutate
+            item = cmplx.decode("utf-8", "strict")
         elif isinstance(cmplx, str):
             item = cmplx
     except Exception as exception:
@@ -569,7 +567,7 @@ def invalidate_version(self, old_version):
                 self._delete_keys_with_version(keys, old_version)
 
                 if cursor == 0:
-                    break  # pragma: no mutate
+                    break
 
         except Exception:
             # Redis error - silently fail
@@ -641,7 +639,7 @@ def clear(self):
                 if keys:
                     self.redis.delete(*keys)
                 if cursor == 0:
-                    break  # pragma: no mutate
+                    break
         except Exception:
             # Redis error - silently fail
             pass

pyproject.toml

@@ -173,13 +173,6 @@ asyncio_default_fixture_loop_scope = "function"
 testpaths = ["posthog/test"]
 norecursedirs = ["integration_tests"]
 
-[tool.mutmut]
-paths_to_mutate = ["posthog/utils.py"]
-do_not_mutate = ["posthog/test/*"]
-tests_dir = ["posthog/test/test_utils.py", "posthog/test/test_size_limited_dict.py"]
-also_copy = ["posthog"]
-pytest_add_cli_args = ["--timeout=30"]
-
 [dependency-groups]
 dev = [
     "claude-agent-sdk>=0.1.50",