Mutmut

mutmut_config.py

@@ -0,0 +1,27 @@
+import os.path
+
+
+def pre_mutation(context):
+    line = context.current_source_line.strip()
+    if line.startswith(("assert False", "@overload")):
+        context.skip = True
+
+    if "= TypeVar" in line:
+        context.skip = True
+
+    return
+    """Extract the coverage contexts if possible and only run the tests
+    matching this data."""
+    if not context.config.coverage_data:
+        # mutmut was run without ``--use-coverage``
+        return
+    fname = os.path.abspath(context.filename)
+    contexts_for_file = context.config.coverage_data.get(fname, {})
+    contexts_for_line = contexts_for_file.get(context.current_line_index, [])
+    print(line)
+    print(contexts_for_line)
+
+    context.config.test_command += " ".join(
+        repr(arg) for arg in contexts_for_line if arg
+    )
+    print(context.config.test_command)

noxfile.py

@@ -43,3 +43,26 @@ def docs(session):
     session.install("poetry")
     session.run("poetry", "install", "--with=doc")
     session.run("mkdocs", "build", *session.posargs)
+
+
+@nox.session(python="python3.10")
+def mutmut(session):
+    session.install("poetry")
+    session.run("poetry", "install", "--with=dev")
+
+    coverage = False
+
+    if coverage:
+        session.run("coverage", "erase")
+
+        session.env["COVERAGE_PROCESS_START"] = str(
+            Path(__file__).parent / "pyproject.toml"
+        )
+        session.env["TOP"] = str(Path(__file__).parent)
+        session.run("pytest", "--doctest-modules", "inline_snapshot", "tests")
+        session.run("coverage", "combine")
+
+    session.run("mutmut", "run", *session.posargs)
+
+    if coverage:
+        session.run("coverage", "erase")

pyproject.toml

@@ -12,6 +12,9 @@ version_files = [
 ]
 version_provider = "poetry"
 
+[tool.coverage.html]
+show_contexts = true
+
 [tool.coverage.report]
 exclude_lines = ["pragma: no cover", "assert False", "raise NotImplemented", "\\.\\.\\."]
 
@@ -51,6 +54,7 @@ python = "^3.7"
 coverage = "^7.2.3"
 coverage-enable-subprocess = "^1.0"
 hypothesis = "^6.75.5"
+mutmut = "^2.4.3"
 mypy = "^1.2.0"
 pytest = "^7.1"
 pytest-subtests = "^0.11.0"

tests/conftest.py

@@ -1 +1,20 @@
 pytest_plugins = "pytester"
+
+import pytest
+import coverage
+
+import os
+
+ctx_key = "COVERAGE_CONTEXT"
+
+
+@pytest.fixture(autouse=True)
+def coverage_context(request):
+    ctx = request.node.nodeid
+    coverage.Coverage.current().switch_context(request.node.nodeid)
+
+    os.environ[ctx_key] = ctx
+
+    yield
+
+    coverage.Coverage.current().switch_context("")

tests/test_inline_snapshot.py

@@ -255,83 +255,83 @@ def test_mutable_values(check_update):
     assert (
         check_update(
             """
-l=[1,2]
+l=[1,[2]]
 assert l==snapshot()
-l.append(3)
+l[1].append(4)
 assert l==snapshot()
     """,
             flags="create",
             number=2,
         )
         == snapshot(
             """
-l=[1,2]
-assert l==snapshot([1, 2])
-l.append(3)
-assert l==snapshot([1, 2, 3])
+l=[1,[2]]
+assert l==snapshot([1, [2]])
+l[1].append(4)
+assert l==snapshot([1, [2, 4]])
 """
         )
     )
 
     assert (
         check_update(
             """
-l=[1,2]
+l=[1,[2]]
 assert l<=snapshot()
-l.append(3)
+l[1].append(4)
 assert l<=snapshot()
     """,
             flags="create",
             number=2,
         )
         == snapshot(
             """
-l=[1,2]
-assert l<=snapshot([1, 2])
-l.append(3)
-assert l<=snapshot([1, 2, 3])
+l=[1,[2]]
+assert l<=snapshot([1, [2]])
+l[1].append(4)
+assert l<=snapshot([1, [2, 4]])
 """
         )
     )
 
     assert (
         check_update(
             """
-l=[1,2]
+l=[1,[2]]
 assert l>=snapshot()
-l.append(3)
+l[1].append(4)
 assert l>=snapshot()
     """,
             flags="create",
             number=2,
         )
         == snapshot(
             """
-l=[1,2]
-assert l>=snapshot([1, 2])
-l.append(3)
-assert l>=snapshot([1, 2, 3])
+l=[1,[2]]
+assert l>=snapshot([1, [2]])
+l[1].append(4)
+assert l>=snapshot([1, [2, 4]])
 """
         )
     )
 
     assert (
         check_update(
             """
-l=[1,2]
+l=[1,[2]]
 assert l in snapshot()
-l.append(3)
+l[1].append(4)
 assert l in snapshot()
     """,
             flags="create",
             number=2,
         )
         == snapshot(
             """
-l=[1,2]
-assert l in snapshot([[1, 2]])
-l.append(3)
-assert l in snapshot([[1, 2, 3]])
+l=[1,[2]]
+assert l in snapshot([[1, [2]]])
+l[1].append(4)
+assert l in snapshot([[1, [2, 4]]])
 """
         )
     )
@@ -661,12 +661,17 @@ def test_plain(check_update):
 def test_string_update(check_update):
     # black --preview wraps strings to keep the line length.
     # string concatenation should produce updates.
-    assert (
-        check_update(
-            'assert "ab" == snapshot("a" "b")', reported_flags="", flags="update"
-        )
-        == 'assert "ab" == snapshot("a" "b")'
-    )
+
+    for prefix in ("", "b"):
+        for quote in "'\"":
+            stmt = f'assert {prefix}"ab" == snapshot({prefix}{quote}a{quote} {prefix}{quote}b{quote})'
+
+            assert check_update(stmt, reported_flags="", flags="update") == stmt
+
+            stmt = f'assert {prefix}"ab" == snapshot({prefix}{quote*3}a{quote*3} {prefix}{quote*3}b{quote*3})'
+            result_stmt = f'assert {prefix}"ab" == snapshot({prefix}"ab")'
+
+            assert check_update(stmt, flags="update") == result_stmt
 
     assert (
         check_update(