Do not warn no-absolute-import multiple times per file (#1725)

CONTRIBUTORS.txt

@@ -142,4 +142,6 @@ Order doesn't matter (not that much, at least ;)
 * Guillaume Peillex: contributor.
+* Daniel Miller: contributor.
+
 * Bryce Guinta: contributor

ChangeLog

@@ -4,6 +4,8 @@ Pylint's ChangeLog
 What's New in Pylint 1.8?
 =========================
+    * Do not display no-absolute-import warning multiple times per file.
+
     * `trailing-comma-tuple` refactor check now extends to assignment with
        more than one element (such as lists)

pylint/checkers/python3.py

@@ -650,6 +650,7 @@ class Python3Checker(checkers.BaseChecker):
             if not self._future_absolute_import:
                 if self.linter.is_message_enabled('no-absolute-import'):
                     self.add_message('no-absolute-import', node=node)
+                    self._future_absolute_import = True
             if not _is_conditional_import(node) and not node.level:
                 self._warn_if_deprecated(node, node.modname, {x[0] for x in node.names})
@@ -660,7 +661,9 @@ class Python3Checker(checkers.BaseChecker):
     def visit_import(self, node):
         if not self._future_absolute_import:
-            self.add_message('no-absolute-import', node=node)
+            if self.linter.is_message_enabled('no-absolute-import'):
+                self.add_message('no-absolute-import', node=node)
+                self._future_absolute_import = True
         if not _is_conditional_import(node):
             for name, _ in node.names:
                 self._warn_if_deprecated(node, name, None)

pylint/test/unittest_checker_python3.py

+# encoding: utf-8
 # Copyright (c) 2014-2015 Brett Cannon <brett@python.org>
 # Copyright (c) 2014-2016 Claudiu Popa <pcmanticore@gmail.com>
@@ -313,12 +314,18 @@ class TestPython3Checker(testutils.CheckerTestCase):
         message = testutils.Message('no-absolute-import', node=node)
         with self.assertAddsMessages(message):
             self.checker.visit_import(node)
+        with self.assertNoMessages():
+            # message should only be added once
+            self.checker.visit_import(node)
     def test_relative_from_import(self):
         node = astroid.extract_node('from os import path  #@')
         message = testutils.Message('no-absolute-import', node=node)
         with self.assertAddsMessages(message):
-            self.checker.visit_import(node)
+            self.checker.visit_importfrom(node)
+        with self.assertNoMessages():
+            # message should only be added once
+            self.checker.visit_importfrom(node)
     def test_absolute_import(self):
         module_import = astroid.parse(
@@ -600,6 +607,7 @@ class TestPython3Checker(testutils.CheckerTestCase):
             absolute_import_message = testutils.Message('no-absolute-import', node=node)
             with self.assertAddsMessages(absolute_import_message):
                 self.checker.visit_importfrom(node)
+            self.checker._future_absolute_import = False
     @python2_only
     def test_bad_import_conditional(self):