Make fix for #223 more readable; add a test and a ChangeLog line.

3 files changed, 82 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 6db44aa..d32c9f8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,10 @@ ChangeLog for Pylint
 --------------------
 
 --
+    * Don't emit import-error for ignored modules. PyLint will not emit import
+      errors for any import which is, or is a subpackage of, a module in
+      the ignored-modules list. Closes issue #223.
+
     * Fix unused-import false positive when the import is used in a
       class assignment. Closes issue #475
 
diff --git a/pylint/checkers/imports.py b/pylint/checkers/imports.py
index eb93b4f..20f8db9 100644
--- a/pylint/checkers/imports.py
+++ b/pylint/checkers/imports.py
@@ -291,12 +291,27 @@ given file (report RP0402 must not be disabled)'}
                 args = '%r (%s)' % (modname, ex)
             else:
                 args = repr(modname)
+
             ignored_modules = get_global_option(self, 'ignored-modules', default=[])
-            while modname and modname not in ignored_modules:
-                modname = modname.rpartition('.')[0]
-            if not modname and not _except_import_error(importnode.parent):
+            for submodule in self._module_hierarchy(modname):
+                if submodule in ignored_modules:
+                    return None
+
+            if not _except_import_error(importnode.parent):
                 self.add_message("import-error", args=args, node=importnode)
 
+    def _module_hierarchy(self, modname):
+        """Returns a list representing the module heirarchy, where each element
+        is the fullly qualified name of the parent of the next element.
+
+        For example,
+            _module_hierarchy('pylint.checkers.ImportsChecker')
+        returns
+            ['pylint', 'pylint.checkers', 'pylint.checkers.ImportsChecker']
+        """
+        names = modname.split('.')
+        return ['.'.join(names[0:i+1]) for i in range(len(names))]
+
     def _check_relative_import(self, modnode, importnode, importedmodnode,
                                importedasname):
         """check relative import. node is either an Import or From node, modname
diff --git a/pylint/test/unittest_checker_imports.py b/pylint/test/unittest_checker_imports.py
new file mode 100644
index 0000000..55948ec
--- /dev/null
+++ b/pylint/test/unittest_checker_imports.py
@@ -0,0 +1,60 @@
+"""Unit tests for the imports checker."""
+import unittest
+
+from astroid import test_utils
+from pylint.checkers import imports
+from pylint.testutils import CheckerTestCase, set_config
+
+class ImportsCheckerTC(CheckerTestCase):
+
+    CHECKER_CLASS = imports.ImportsChecker
+
+    def test_bitbucket_issue_78(self):
+        """ Issue 78 report a false positive for unused-module """
+        module = test_utils.build_module("""
+        from sys import path
+        path += ['stuff']
+        def func():
+            other = 1
+            return len(other)
+        """)
+        with self.assertNoMessages():
+            self.walk(module)
+
+    @set_config(ignored_modules=('external_module', 'fake_module.submodule'))
+    def test_import_error_skipped(self):
+        """Make sure that imports do not emit a 'import-error' when the
+        module is configured to be ignored."""
+
+        node = test_utils.extract_node("""
+        from external_module import anything
+        """)
+        with self.assertNoMessages():
+            self.checker.visit_from(node)
+
+        node = test_utils.extract_node("""
+        from external_module.another_module import anything
+        """)
+        with self.assertNoMessages():
+            self.checker.visit_from(node)
+
+        node = test_utils.extract_node("""
+        import external_module
+        """)
+        with self.assertNoMessages():
+            self.checker.visit_import(node)
+
+        node = test_utils.extract_node("""
+        from fake_module.submodule import anything
+        """)
+        with self.assertNoMessages():
+            self.checker.visit_from(node)
+
+        node = test_utils.extract_node("""
+        from fake_module.submodule.deeper import anything
+        """)
+        with self.assertNoMessages():
+            self.checker.visit_from(node)
+
+if __name__ == '__main__':
+    unittest.main()