Add checker to identify multiple imports on one line.

Fixes issue #598. Had to modify some functional tests to ignore new message.

7 files changed, 36 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 2ed0746..8c9811c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,9 +2,12 @@ ChangeLog for Pylint
 --------------------
 
 --
+    * Add checker to identify multiple imports on one line.
+      Closes issue #598.
+
     * Fix unused-argument false positive when the "+=" operator is used.
       Closes issue #518.
-	
+
     * 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.
diff --git a/pylint/checkers/imports.py b/pylint/checkers/imports.py
index a5a2f28..ae8df55 100644
--- a/pylint/checkers/imports.py
+++ b/pylint/checkers/imports.py
@@ -173,6 +173,11 @@ MSGS = {
               'misplaced-future',
               'Python 2.5 and greater require __future__ import to be the \
               first non docstring statement in the module.'),
+
+    'W0411': ('Multiple imports on one line (%s)',
+              'multiple-imports',
+              'Used when import statement importing multiple modules is '
+              'detected.'),
     }
 
 class ImportsChecker(BaseChecker):
@@ -254,7 +259,10 @@ given file (report RP0402 must not be disabled)'}
     def visit_import(self, node):
         """triggered when an import statement is seen"""
         modnode = node.root()
-        for name, _ in node.names:
+        names = [name for name, _ in node.names]
+        if len(names) >= 2:
+            self.add_message('multiple-imports', args=', '.join(names), node=node)
+        for name in names:
             self._check_deprecated_module(node, name)
             importedmodnode = self.get_imported_module(node, name)
             if importedmodnode is None:
diff --git a/pylint/test/functional/bad_exception_context.py b/pylint/test/functional/bad_exception_context.py
index f386343..af3e4fb 100644
--- a/pylint/test/functional/bad_exception_context.py
+++ b/pylint/test/functional/bad_exception_context.py
@@ -1,6 +1,6 @@
 """Check that raise ... from .. uses a proper exception context """
 
-# pylint: disable=unreachable, import-error
+# pylint: disable=unreachable, import-error, multiple-imports
 
 import socket, unknown
 
diff --git a/pylint/test/functional/invalid_exceptions_caught.py b/pylint/test/functional/invalid_exceptions_caught.py
index 2392ab0..545954d 100644
--- a/pylint/test/functional/invalid_exceptions_caught.py
+++ b/pylint/test/functional/invalid_exceptions_caught.py
@@ -1,5 +1,5 @@
 """Test for catching non-exceptions."""
-# pylint: disable=too-many-ancestors, no-absolute-import, import-error
+# pylint: disable=too-many-ancestors, no-absolute-import, import-error, multiple-imports
 from __future__ import print_function
 
 import socket, binascii
diff --git a/pylint/test/functional/multiple_imports.py b/pylint/test/functional/multiple_imports.py
new file mode 100644
index 0000000..9008dcc
--- /dev/null
+++ b/pylint/test/functional/multiple_imports.py
@@ -0,0 +1,2 @@
+# pylint: disable=missing-docstring, unused-import
+import os, socket  # [multiple-imports]
diff --git a/pylint/test/functional/multiple_imports.txt b/pylint/test/functional/multiple_imports.txt
new file mode 100644
index 0000000..a5df51e
--- /dev/null
+++ b/pylint/test/functional/multiple_imports.txt
@@ -0,0 +1 @@
+multiple-imports:2::Multiple imports on one line (os, socket)
diff --git a/pylint/test/unittest_checker_imports.py b/pylint/test/unittest_checker_imports.py
index 8832878..f5e6bbb 100644
--- a/pylint/test/unittest_checker_imports.py
+++ b/pylint/test/unittest_checker_imports.py
@@ -10,7 +10,10 @@ class ImportsCheckerTC(CheckerTestCase):
 
     CHECKER_CLASS = imports.ImportsChecker
 
-    @set_config(ignored_modules=('external_module', 'fake_module.submodule'))
+    @set_config(ignored_modules=('external_module',
+                                 'fake_module.submodule',
+                                 'foo',
+                                 'bar'))
     def test_import_error_skipped(self):
         """Make sure that imports do not emit a 'import-error' when the
         module is configured to be ignored."""
@@ -45,6 +48,20 @@ class ImportsCheckerTC(CheckerTestCase):
         with self.assertNoMessages():
             self.checker.visit_importfrom(node)
 
+        node = test_utils.extract_node("""
+        import foo, bar
+        """)
+        msg = Message('multiple-imports', node=node, args='foo, bar')
+        with self.assertAddsMessages(msg):
+            self.checker.visit_import(node)
+
+        node = test_utils.extract_node("""
+        import foo
+        import bar
+        """)
+        with self.assertNoMessages():
+            self.checker.visit_import(node)
+
     def test_visit_importfrom(self):
         """
         Test that duplicate imports on single line raise 'reimported'.