Allow the context plugin to check if the controller is running or not. Fixes #685.

Author: ionelmc

src/pytest_cov/engine.py

@@ -87,6 +87,7 @@ def __init__(self, options: argparse.Namespace, config: Union[None, object], nod
         self.failed_workers = []
         self.topdir = os.fspath(Path.cwd())
         self.is_collocated = None
+        self.started = False
 
     @contextlib.contextmanager
     def ensure_topdir(self):
@@ -97,13 +98,21 @@ def ensure_topdir(self):
 
     @_ensure_topdir
     def pause(self):
+        self.started = False
         self.cov.stop()
         self.unset_env()
 
     @_ensure_topdir
     def resume(self):
         self.cov.start()
         self.set_env()
+        self.started = True
+
+    def start(self):
+        self.started = True
+
+    def finish(self):
+        self.started = False
 
     @_ensure_topdir
     def set_env(self):
@@ -295,9 +304,12 @@ def start(self):
         self.cov.start()
         self.set_env()
 
+        super().start()
+
     @_ensure_topdir
     def finish(self):
         """Stop coverage, save data to file and set the list of coverage objects to report on."""
+        super().finish()
 
         self.unset_env()
         self.cov.stop()
@@ -440,10 +452,13 @@ def start(self):
         )
         self.cov.start()
         self.set_env()
+        super().start()
 
     @_ensure_topdir
     def finish(self):
         """Stop coverage and send relevant info back to the master."""
+        super().finish()
+
         self.unset_env()
         self.cov.stop()
 

src/pytest_cov/plugin.py

@@ -284,7 +284,7 @@ def pytest_sessionstart(self, session):
             self.start(engine.Central)
 
         if self.options.cov_context == 'test':
-            session.config.pluginmanager.register(TestContextPlugin(self.cov_controller.cov), '_cov_contexts')
+            session.config.pluginmanager.register(TestContextPlugin(self.cov_controller), '_cov_contexts')
 
     @pytest.hookimpl(optionalhook=True)
     def pytest_configure_node(self, node):
@@ -408,8 +408,10 @@ def pytest_runtest_call(self, item):
 
 
 class TestContextPlugin:
-    def __init__(self, cov):
-        self.cov = cov
+    cov_controller: 'CovController'
+
+    def __init__(self, cov_controller):
+        self.cov_controller = cov_controller
 
     def pytest_runtest_setup(self, item):
         self.switch_context(item, 'setup')
@@ -421,9 +423,10 @@ def pytest_runtest_call(self, item):
         self.switch_context(item, 'run')
 
     def switch_context(self, item, when):
-        context = f'{item.nodeid}|{when}'
-        self.cov.switch_context(context)
-        os.environ['COV_CORE_CONTEXT'] = context
+        if self.cov_controller.started:
+            context = f'{item.nodeid}|{when}'
+            self.cov_controller.cov.switch_context(context)
+            os.environ['COV_CORE_CONTEXT'] = context
 
 
 @pytest.fixture

tests/test_pytest_cov.py

@@ -1942,6 +1942,36 @@ def test_contexts_not_supported(testdir):
     assert result.ret != 0
 
 
+def test_contexts_no_cover(testdir):
+    script = testdir.makepyfile("""
+import pytest
+
+def foobar():
+    return 1
+
+def test_with_coverage():
+    foobar()
+
+@pytest.mark.no_cover()
+def test_without_coverage():
+    foobar()
+""")
+    result = testdir.runpytest(
+        '-v',
+        '--cov-context=test',
+        '--cov=test_contexts_no_cover',
+        script,
+    )
+    result.stdout.fnmatch_lines(
+        [
+            'test_contexts_no_cover.py       8      1    88%',
+            'TOTAL                           8      1    88%',
+        ]
+    )
+    assert result.stderr.lines == []
+    assert result.ret == 0
+
+
 def test_issue_417(testdir):
     # https://github.com/pytest-dev/pytest-cov/issues/417
     whatever = testdir.maketxtfile(whatever='')