GTTF: Print much better error message for dependency cycles.

pylib/gyp/input_test.py

+#!/usr/bin/env python
+
+# Copyright 2013 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Unit tests for the input.py file."""
+
+import gyp.input
+import unittest
+import sys
+
+
+class TestFindCycles(unittest.TestCase):
+  def setUp(self):
+    self.nodes = {}
+    for x in ('a', 'b', 'c', 'd', 'e'):
+      self.nodes[x] = gyp.input.DependencyGraphNode(x)
+
+  def _create_dependency(self, dependent, dependency):
+    dependent.dependencies.append(dependency)
+    dependency.dependents.append(dependent)
+
+  def test_no_cycle_empty_graph(self):
+    for label, node in self.nodes.iteritems():
+      self.assertEquals([], node.FindCycles())
+
+  def test_no_cycle_line(self):
+    self._create_dependency(self.nodes['a'], self.nodes['b'])
+    self._create_dependency(self.nodes['b'], self.nodes['c'])
+    self._create_dependency(self.nodes['c'], self.nodes['d'])
+
+    for label, node in self.nodes.iteritems():
+      self.assertEquals([], node.FindCycles())
+
+  def test_no_cycle_dag(self):
+    self._create_dependency(self.nodes['a'], self.nodes['b'])
+    self._create_dependency(self.nodes['a'], self.nodes['c'])
+    self._create_dependency(self.nodes['b'], self.nodes['c'])
+
+    for label, node in self.nodes.iteritems():
+      self.assertEquals([], node.FindCycles())
+
+  def test_cycle_self_reference(self):
+    self._create_dependency(self.nodes['a'], self.nodes['a'])
+
+    self.assertEquals([(self.nodes['a'], self.nodes['a'])],
+                      self.nodes['a'].FindCycles())
+
+  def test_cycle_two_nodes(self):
+    self._create_dependency(self.nodes['a'], self.nodes['b'])
+    self._create_dependency(self.nodes['b'], self.nodes['a'])
+
+    self.assertEquals([(self.nodes['a'], self.nodes['b'], self.nodes['a'])],
+                      self.nodes['a'].FindCycles())
+    self.assertEquals([(self.nodes['b'], self.nodes['a'], self.nodes['b'])],
+                      self.nodes['b'].FindCycles())
+
+  def test_two_cycles(self):
+    self._create_dependency(self.nodes['a'], self.nodes['b'])
+    self._create_dependency(self.nodes['b'], self.nodes['a'])
+
+    self._create_dependency(self.nodes['b'], self.nodes['c'])
+    self._create_dependency(self.nodes['c'], self.nodes['b'])
+
+    cycles = self.nodes['a'].FindCycles()
+    self.assertTrue(
+       (self.nodes['a'], self.nodes['b'], self.nodes['a']) in cycles)
+    self.assertTrue(
+       (self.nodes['b'], self.nodes['c'], self.nodes['b']) in cycles)
+    self.assertEquals(2, len(cycles))
+
+  def test_big_cycle(self):
+    self._create_dependency(self.nodes['a'], self.nodes['b'])
+    self._create_dependency(self.nodes['b'], self.nodes['c'])
+    self._create_dependency(self.nodes['c'], self.nodes['d'])
+    self._create_dependency(self.nodes['d'], self.nodes['e'])
+    self._create_dependency(self.nodes['e'], self.nodes['a'])
+
+    self.assertEquals([(self.nodes['a'],
+                        self.nodes['b'],
+                        self.nodes['c'],
+                        self.nodes['d'],
+                        self.nodes['e'],
+                        self.nodes['a'])],
+                      self.nodes['a'].FindCycles())
+
+
+if __name__ == '__main__':
+  unittest.main()