Improve CLI interface of C++ enums to Java generator

build/android/gyp/java_cpp_enum_tests.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Tests for enum_preprocess.py.
 
 This test suite containss various tests for the C++ -> Java enum generator.
 """
 
 import collections
 import optparse
 import os
 import sys
 import unittest
 
+import java_cpp_enum
 from java_cpp_enum import EnumDefinition, GenerateOutput, GetScriptName
 from java_cpp_enum import HeaderParser
 
 sys.path.append(os.path.join(os.path.dirname(__file__), "gyp"))
 from util import build_utils
 
 class TestPreprocess(unittest.TestCase):
   def testOutput(self):
     definition = EnumDefinition(original_enum_name='ClassName',
                                 enum_package='some.package',
@@ skipping 117 matching lines @@
   def testParseThrowsOnUnknownDirective(self):
     test_data = """
       // GENERATED_JAVA_UNKNOWN: Value
       enum EnumName {
         VALUE_ONE,
       };
     """.split('\n')
     with self.assertRaises(Exception):
       HeaderParser(test_data).ParseDefinitions()
 
+  def testParseReturnsEmptyListWithoutDirectives(self):
+    test_data = """
+      enum EnumName {
+        VALUE_ONE,
+      };
+    """.split('\n')
+    self.assertEqual([], HeaderParser(test_data).ParseDefinitions())
+
   def testParseEnumClass(self):
     test_data = """
       // GENERATED_JAVA_ENUM_PACKAGE: test.namespace
       enum class Foo {
         FOO_A,
       };
     """.split('\n')
     definitions = HeaderParser(test_data).ParseDefinitions()
     self.assertEqual(1, len(definitions))
     definition = definitions[0]
@@ skipping 232 matching lines @@
 
   def testImplicitPrefixStrippingRequiresAllConstantsToBePrefixed(self):
     definition = EnumDefinition(original_enum_name='Name',
                                 enum_package='p')
     definition.AppendEntry('A', None)
     definition.AppendEntry('B', None)
     definition.AppendEntry('NAME_LAST', None)
     definition.Finalize()
     self.assertEqual(['A', 'B', 'NAME_LAST'], definition.entries.keys())
 
+  def testGenerateThrowsOnEmptyInput(self):
+    with self.assertRaises(Exception):
+      original_do_parse = java_cpp_enum.DoParseHeaderFile
+      try:
+        java_cpp_enum.DoParseHeaderFile = lambda _: []
+        java_cpp_enum.DoGenerate('dir', ['file'])
+      finally:
+        java_cpp_enum.DoParseHeaderFile = original_do_parse
+
 def main(argv):
   parser = optparse.OptionParser()
   parser.add_option("--stamp", help="File to touch on success.")
   options, _ = parser.parse_args(argv)
 
   suite = unittest.TestLoader().loadTestsFromTestCase(TestPreprocess)
   unittest.TextTestRunner(verbosity=0).run(suite)
 
   if options.stamp:
     build_utils.Touch(options.stamp)
 
 if __name__ == '__main__':
   main(sys.argv[1:])