Re-use CheckUniqueFilenames for test_collector.py

4 files changed, 42 insertions, 45 deletions

diff --git a/coverage/test_helpers.py b/coverage/test_helpers.py
index a42fe3b4..65d99779 100644
--- a/coverage/test_helpers.py
+++ b/coverage/test_helpers.py
@@ -117,6 +117,7 @@ class StdStreamCapturingMixin(TestCase):
         self.old_stdout = sys.stdout
         self.captured_stdout = StringIO()
         sys.stdout = Tee(sys.stdout, self.captured_stdout)
+
         self.old_stderr = sys.stderr
         self.captured_stderr = StringIO()
         sys.stderr = self.captured_stderr
diff --git a/tests/helpers.py b/tests/helpers.py
new file mode 100644
index 00000000..db20d798
--- /dev/null
+++ b/tests/helpers.py
@@ -0,0 +1,25 @@
+"""Helpers for coverage.py tests."""
+
+
+class CheckUniqueFilenames(object):
+    """Asserts the uniqueness of filenames passed to a function."""
+    def __init__(self, wrapped):
+        self.filenames = set()
+        self.wrapped = wrapped
+
+    @classmethod
+    def hook(cls, cov, method_name):
+        """Replace a method with our checking wrapper."""
+        method = getattr(cov, method_name)
+        hook = cls(method)
+        setattr(cov, method_name, hook.wrapper)
+        return hook
+
+    def wrapper(self, filename, *args, **kwargs):
+        """The replacement method.  Check that we don't have dupes."""
+        assert filename not in self.filenames, (
+            "Filename %r passed to %r twice" % (filename, self.wrapped)
+            )
+        self.filenames.add(filename)
+        ret = self.wrapped(filename, *args, **kwargs)
+        return ret
diff --git a/tests/test_collector.py b/tests/test_collector.py
index 5a8325c7..26360091 100644
--- a/tests/test_collector.py
+++ b/tests/test_collector.py
@@ -1,11 +1,11 @@
 """Tests of coverage/collector.py and other collectors."""
 
-import re
+import os.path
 
 import coverage
-from coverage.backward import StringIO
 
 from tests.coveragetest import CoverageTest
+from tests.helpers import CheckUniqueFilenames
 
 
 class CollectorTest(CoverageTest):
@@ -13,8 +13,6 @@ class CollectorTest(CoverageTest):
 
     def test_should_trace_cache(self):
         # The tracers should only invoke should_trace once for each file name.
-        # TODO: Might be better to do this with a mocked _should_trace,
-        # rather than by examining debug output.
 
         # Make some files that invoke each other.
         self.make_file("f1.py", """\
@@ -35,22 +33,15 @@ class CollectorTest(CoverageTest):
                 func(i)
             """)
 
-        # Trace one file, but not the other, and get the debug output.
-        debug_out = StringIO()
-        cov = coverage.coverage(include=["f1.py"], debug=['trace'])
-        cov._debug_file = debug_out
+        # Trace one file, but not the other. CheckUniqueFilenames will assert
+        # that _should_trace hasn't been called twice for the same file.
+        cov = coverage.coverage(include=["f1.py"])
+        should_trace_hook = CheckUniqueFilenames.hook(cov, '_should_trace')
 
         # Import the Python file, executing it.
         self.start_import_stop(cov, "f2")
 
-        # Grab all the filenames mentioned in debug output, there should be no
-        # duplicates.
-        trace_lines = [
-            l for l in debug_out.getvalue().splitlines()
-            if l.startswith(("Tracing ", "Not tracing "))
-        ]
-        filenames = [re.search(r"'[^']+'", l).group() for l in trace_lines]
-        self.assertEqual(len(filenames), len(set(filenames)))
-
-        # Double-check that the tracing messages are in there somewhere.
-        self.assertGreater(len(filenames), 5)
+        # Double-check that our files were checked.
+        abs_files = set(os.path.abspath(f) for f in should_trace_hook.filenames)
+        self.assertIn(os.path.abspath("f1.py"), abs_files)
+        self.assertIn(os.path.abspath("f2.py"), abs_files)
diff --git a/tests/test_plugins.py b/tests/test_plugins.py
index 48b0498c..190096bd 100644
--- a/tests/test_plugins.py
+++ b/tests/test_plugins.py
@@ -10,6 +10,7 @@ from coverage.control import Plugins
 import coverage.plugin
 
 from tests.coveragetest import CoverageTest
+from tests.helpers import CheckUniqueFilenames
 
 
 class FakeConfig(object):
@@ -215,8 +216,8 @@ class FileTracerTest(CoverageTest):
             """)
 
         cov = coverage.Coverage()
-        should_trace_hook = CheckUnique.hook(cov, '_should_trace')
-        check_include_hook = CheckUnique.hook(cov, '_check_include_omit_etc')
+        should_trace_hook = CheckUniqueFilenames.hook(cov, '_should_trace')
+        check_include_hook = CheckUniqueFilenames.hook(cov, '_check_include_omit_etc')
         cov.config["run:plugins"] = ["tests.plugin1"]
 
         # Import the Python file, executing it.
@@ -250,7 +251,7 @@ class FileTracerTest(CoverageTest):
             from render import helper, render
 
             assert render("foo_7.html", 4) == "[foo_7.html @ 4]"
-            # Render foo_7.html again to trigger the callback snoopers.
+            # Render foo_7.html again to try the CheckUniqueFilenames asserts.
             render("foo_7.html", 4)
 
             assert helper(42) == 43
@@ -259,8 +260,8 @@ class FileTracerTest(CoverageTest):
             """)
 
         cov = coverage.Coverage()
-        should_trace_hook = CheckUnique.hook(cov, '_should_trace')
-        check_include_hook = CheckUnique.hook(cov, '_check_include_omit_etc')
+        should_trace_hook = CheckUniqueFilenames.hook(cov, '_should_trace')
+        check_include_hook = CheckUniqueFilenames.hook(cov, '_check_include_omit_etc')
         cov.config["run:plugins"] = ["tests.plugin2"]
 
         self.start_import_stop(cov, "caller")
@@ -274,24 +275,3 @@ class FileTracerTest(CoverageTest):
         _, statements, missing, _ = cov.analysis("bar_4.html")
         self.assertEqual(statements, [1, 2, 3, 4])
         self.assertEqual(missing, [1, 4])
-
-
-class CheckUnique(object):
-    """Asserts the uniqueness of filenames passed to a function."""
-    def __init__(self, wrapped):
-        self.filenames = set()
-        self.wrapped = wrapped
-
-    @classmethod
-    def hook(cls, cov, method_name):
-        """Replace a method with our checking wrapper."""
-        method = getattr(cov, method_name)
-        hook = cls(method)
-        setattr(cov, method_name, hook.wrapper)
-        return hook
-
-    def wrapper(self, filename, *args, **kwargs):
-        """The replacement method.  Check that we don't have dupes."""
-        assert filename not in self.filenames
-        self.filenames.add(filename)
-        return self.wrapped(filename, *args, **kwargs)