Don't get confused by namespace packages #456

3 files changed, 34 insertions, 1 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index c007a235..a6f0efa4 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -42,12 +42,17 @@ Unreleased
 - Officially support PyPy 5.1, which required no changes, just updates to the
   docs.
 
+- It's never been possible to pass a namespace module to one of the analysis
+  functions, but now at least we raise a more specific error message, rather
+  than getting confused. (`issue 456`_)
+
 - Make a small tweak to how we compare threads, to avoid buggy custom
   comparison code in thread classes. (`issue 245`_)
 
 .. _issue 90: https://bitbucket.org/ned/coveragepy/issues/90/lambda-expression-confuses-branch
 .. _issue 245: https://bitbucket.org/ned/coveragepy/issues/245/change-solution-for-issue-164
 .. _issue 440: https://bitbucket.org/ned/coveragepy/issues/440/yielded-twisted-failure-marked-as-missed
+.. _issue 456: https://bitbucket.org/ned/coveragepy/issues/456/coverage-breaks-with-implicit-namespaces
 .. _issue 460: https://bitbucket.org/ned/coveragepy/issues/460/confusing-html-report-for-certain-partial
 .. _issue 469: https://bitbucket.org/ned/coveragepy/issues/469/strange-1-line-number-in-branch-coverage
 .. _issue 472: https://bitbucket.org/ned/coveragepy/issues/472/html-report-indents-incorrectly-for-one
diff --git a/coverage/python.py b/coverage/python.py
index 0cd2181c..8e98bea8 100644
--- a/coverage/python.py
+++ b/coverage/python.py
@@ -4,10 +4,13 @@
 """Python source expertise for coverage.py"""
 
 import os.path
+import types
 import zipimport
 
 from coverage import env, files
-from coverage.misc import contract, expensive, NoSource, join_regex, isolate_module
+from coverage.misc import (
+    contract, CoverageException, expensive, NoSource, join_regex, isolate_module,
+)
 from coverage.parser import PythonParser
 from coverage.phystokens import source_token_lines, source_encoding
 from coverage.plugin import FileReporter
@@ -94,6 +97,10 @@ class PythonFileReporter(FileReporter):
 
         if hasattr(morf, '__file__'):
             filename = morf.__file__
+        elif isinstance(morf, types.ModuleType):
+            # A module should have had .__file__, otherwise we can't use it.
+            # This could be a PEP-420 namespace package.
+            raise CoverageException("Module {0} has no file".format(morf))
         else:
             filename = morf
 
diff --git a/tests/test_api.py b/tests/test_api.py
index 3ea5b3ef..4c038519 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -9,6 +9,7 @@ import sys
 import textwrap
 
 import coverage
+from coverage import env
 from coverage.backward import StringIO
 from coverage.misc import CoverageException
 
@@ -322,6 +323,26 @@ class ApiTest(CoverageTest):
         self.assert_exists(".coverage.foo")
 
 
+class NamespaceModuleTest(CoverageTest):
+    """Test PEP-420 namespace modules."""
+
+    def setUp(self):
+        super(NamespaceModuleTest, self).setUp()
+        if env.PYVERSION < (3, 3):
+            self.skip("Python before 3.3 doesn't have namespace packages")
+
+    def test_explicit_namespace_module(self):
+        self.make_file("namespace/package/module.py", "VAR = 1\n")
+        self.make_file("main.py", "import namespace\n")
+
+        cov = coverage.Coverage()
+        self.start_import_stop(cov, "main")
+
+        with self.assertRaisesRegex(CoverageException, r"Module .* has no file"):
+            cov.analysis(sys.modules['namespace'])
+
+
+
 class UsingModulesMixin(object):
     """A mixin for importing modules from test/modules and test/moremodules."""