Mojo C++ bindings: fail validation test if no test data found and add data dependency.

mojo/public/cpp/bindings/tests/validation_unittest.cc

 // 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.
 
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <algorithm>
 #include <string>
 #include <utility>
@@ skipping 147 matching lines @@
   message->mutable_handles()->resize(num_handles);
 
   return true;
 }
 
 void RunValidationTests(const std::string& prefix,
                         MessageReceiver* test_message_receiver) {
   std::vector<std::string> names =
       EnumerateSourceRootRelativeDirectory(GetPath("", ""));
   std::vector<std::string> tests = GetMatchingTests(names, prefix);
+  ASSERT_FALSE(tests.empty());
 
   for (size_t i = 0; i < tests.size(); ++i) {
     Message message;
     std::string expected;
     ASSERT_TRUE(ReadTestCase(tests[i], &message, &expected));
 
     std::string result;
     base::RunLoop run_loop;
     mojo::internal::ValidationErrorObserverForTesting observer(
         run_loop.QuitClosure());
@@ skipping 311 matching lines @@
   EXPECT_TRUE(IsKnownEnumValue(static_cast<StructWithEnum::EnumWithin>(0)));
   EXPECT_TRUE(IsKnownEnumValue(static_cast<StructWithEnum::EnumWithin>(1)));
   EXPECT_TRUE(IsKnownEnumValue(static_cast<StructWithEnum::EnumWithin>(2)));
   EXPECT_TRUE(IsKnownEnumValue(static_cast<StructWithEnum::EnumWithin>(3)));
   EXPECT_FALSE(IsKnownEnumValue(static_cast<StructWithEnum::EnumWithin>(4)));
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace mojo