WIP

Author: nedbat

src/pytest_cov/plugin.py

@@ -4,6 +4,7 @@
 import warnings
 
 import pytest
+import coverage
 from coverage.misc import CoverageException
 
 from . import compat
@@ -48,6 +49,16 @@ def validate_fail_under(num_str):
         return float(num_str)
 
 
+def validate_contexts(arg):
+    if coverage.version_info <= (5, 0):
+        msg = 'Contexts are only supported with coverage.py >= 5.x'
+        raise argparse.ArgumentTypeError(msg)
+    if arg != "test":
+        msg = '--cov-contexts=test is the only supported value'
+        raise argparse.ArgumentTypeError(msg)
+    return arg
+
+
 class StoreReport(argparse.Action):
     def __call__(self, parser, namespace, values, option_string=None):
         report_type, file = values
@@ -88,6 +99,9 @@ def pytest_addoption(parser):
                          'Default: False')
     group.addoption('--cov-branch', action='store_true', default=None,
                     help='Enable branch coverage.')
+    group.addoption('--cov-contexts', action='store', metavar='CONTEXT',
+                    type=validate_contexts,
+                    help='Dynamic contexts to use. "test" for now.')
 
 
 def _prepare_cov_source(cov_source):
@@ -151,6 +165,9 @@ def __init__(self, options, pluginmanager, start=True):
         elif start:
             self.start(engine.Central)
 
+        if getattr(options, 'cov_contexts', None) == 'test':
+            pluginmanager.register(TestContextPlugin(self.cov_controller.cov), '_cov_contexts')
+
         # worker is started in pytest hook
 
     def start(self, controller_cls, config=None, nodeid=None):
@@ -308,6 +325,24 @@ def pytest_runtest_call(self, item):
             yield
 
 
+class TestContextPlugin(object):
+    def __init__(self, cov):
+        self.cov = cov
+
+    def pytest_runtest_setup(self, item):
+        self.switch_context(item, 'setup')
+
+    def pytest_runtest_teardown(self, item):
+        self.switch_context(item, 'teardown')
+
+    def pytest_runtest_call(self, item):
+        self.switch_context(item, 'run')
+
+    def switch_context(self, item, when):
+        context = "{item.nodeid}|{when}".format(item=item, when=when)
+        self.cov.switch_context(context)
+
+
 @pytest.fixture
 def no_cover():
     """A pytest fixture to disable coverage."""

tests/test_pytest_cov.py

@@ -1,6 +1,7 @@
 import glob
 import os
 import platform
+import sqlite3
 import subprocess
 import sys
 from itertools import chain
@@ -1928,3 +1929,59 @@ def test_cov_and_no_cov(testdir):
                                script)
 
     assert result.ret == 0
+
+
+CONTEXTFUL_TESTS = '''\
+import unittest
+
+def test_one():
+    assert 1 == 1
+
+def test_two():
+    assert 2 == 2
+
+class OldStyleTests(unittest.TestCase):
+    def setUp(self):
+        self.three = 3
+    def tearDown(self):
+        self.three = None
+    def test_three(self):
+        assert self.three == 3
+'''
+
+@pytest.mark.skipif("coverage.version_info < (5, 0)")
+@xdist_params
+def test_contexts(testdir, opts):
+    script = testdir.makepyfile(CONTEXTFUL_TESTS)
+    result = testdir.runpytest('-v',
+                               '--cov=%s' % script.dirpath(),
+                               '--cov-contexts=test',
+                               script,
+                               *opts.split()
+                               )
+    result.stdout.fnmatch_lines([
+        'test_contexts* 100%*',
+    ])
+    con = sqlite3.connect(".coverage")
+    cur = con.cursor()
+    contexts = set(r[0] for r in cur.execute("select context from context"))
+    assert contexts == {
+        '',
+        'test_contexts.py::test_two|run',
+        'test_contexts.py::test_one|run',
+        'test_contexts.py::OldStyleTests::test_three|run',
+        }
+
+
+@pytest.mark.skipif("coverage.version_info >= (5, 0)")
+def test_contexts_not_supported(testdir):
+    script = testdir.makepyfile(CONTEXTFUL_TESTS)
+    result = testdir.runpytest('-v',
+                               '--cov=%s' % script.dirpath(),
+                               '--cov-contexts=test',
+                               script,
+                               )
+    result.stderr.fnmatch_lines([
+        '*argument --cov-contexts: Contexts are only supported with coverage.py >= 5.x',
+    ])
+    assert result.ret != 0