diff --git a/objectivec/Tests/GPBTestUtilities.h b/objectivec/Tests/GPBTestUtilities.h
new file mode 100644
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--- /dev/null
+++ b/objectivec/Tests/GPBTestUtilities.h
@@ -0,0 +1,100 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#import <XCTest/XCTest.h>
+
+@class TestAllExtensions;
+@class TestAllTypes;
+@class TestMap;
+@class TestPackedTypes;
+@class TestPackedExtensions;
+@class TestUnpackedTypes;
+@class TestUnpackedExtensions;
+@class GPBExtensionRegistry;
+
+
+// Helper for uses of C arrays in tests cases.
+#ifndef GPBARRAYSIZE
+#define GPBARRAYSIZE(a) ((sizeof(a) / sizeof((a[0]))))
+#endif  // GPBARRAYSIZE
+
+
+// The number of repetitions of any repeated objects inside of test messages.
+extern const uint32_t kGPBDefaultRepeatCount;
+
+@interface GPBTestCase : XCTestCase
+
+- (void)setAllFields:(TestAllTypes *)message repeatedCount:(uint32_t)count;
+- (void)clearAllFields:(TestAllTypes *)message;
+- (void)setAllExtensions:(TestAllExtensions *)message
+           repeatedCount:(uint32_t)count;
+- (void)setPackedFields:(TestPackedTypes *)message
+          repeatedCount:(uint32_t)count;
+- (void)setUnpackedFields:(TestUnpackedTypes *)message
+            repeatedCount:(uint32_t)count;
+- (void)setPackedExtensions:(TestPackedExtensions *)message
+              repeatedCount:(uint32_t)count;
+- (void)setUnpackedExtensions:(TestUnpackedExtensions *)message
+              repeatedCount:(uint32_t)count;
+- (void)setAllMapFields:(TestMap *)message numEntries:(uint32_t)count;
+
+- (TestAllTypes *)allSetRepeatedCount:(uint32_t)count;
+- (TestAllExtensions *)allExtensionsSetRepeatedCount:(uint32_t)count;
+- (TestPackedTypes *)packedSetRepeatedCount:(uint32_t)count;
+- (TestPackedExtensions *)packedExtensionsSetRepeatedCount:(uint32_t)count;
+
+- (void)assertAllFieldsSet:(TestAllTypes *)message
+             repeatedCount:(uint32_t)count;
+- (void)assertAllExtensionsSet:(TestAllExtensions *)message
+                 repeatedCount:(uint32_t)count;
+- (void)assertRepeatedFieldsModified:(TestAllTypes *)message
+                       repeatedCount:(uint32_t)count;
+- (void)assertRepeatedExtensionsModified:(TestAllExtensions *)message
+                           repeatedCount:(uint32_t)count;
+- (void)assertExtensionsClear:(TestAllExtensions *)message;
+- (void)assertClear:(TestAllTypes *)message;
+- (void)assertPackedFieldsSet:(TestPackedTypes *)message
+                repeatedCount:(uint32_t)count;
+- (void)assertPackedExtensionsSet:(TestPackedExtensions *)message
+                    repeatedCount:(uint32_t)count;
+
+- (void)modifyRepeatedExtensions:(TestAllExtensions *)message;
+- (void)modifyRepeatedFields:(TestAllTypes *)message;
+
+- (GPBExtensionRegistry *)extensionRegistry;
+
+- (NSData *)getDataFileNamed:(NSString *)name dataToWrite:(NSData *)dataToWrite;
+
+- (void)assertAllFieldsKVCMatch:(TestAllTypes *)message;
+- (void)setAllFieldsViaKVC:(TestAllTypes *)message
+             repeatedCount:(uint32_t)count;
+- (void)assertClearKVC:(TestAllTypes *)message;
+
+@end