IOS-2794 Test subdata copying

PantomimeFramework/PantomimeFrameworkTests/Pantomime/NSData+ExtensionsTest.m

@@ -205,6 +205,24 @@ static NSString *text = @"My test\t Text containing 1234567890ß? stuff";
     [self assertDataByTrimmingWhiteSpacesFromTestStringUsedInFormat:testFormat];
 }
 
+#pragma mark - subdata
+
+/// This test proves that `[NSData subdataWithRange]` _copies_ the bytes it covers to a new buffer.
+- (void)testSubdataWithRange
+{
+    NSString *testStr = @"<35BE75EB.74E6.4CB7.9C5D.432B241FDF90@pretty.Easy.privacy>";
+    NSData *testData = [testStr dataUsingEncoding:NSASCIIStringEncoding];
+
+    NSRange r1 = NSMakeRange(0, 5);
+    NSData *subDataFromStart = [testData subdataWithRange:r1];
+    XCTAssertNotEqual([testData bytes], [subDataFromStart bytes]);
+
+    NSInteger offset = 5;
+    NSRange r2 = NSMakeRange(offset, 5);
+    NSData *subDataFromOffset = [testData subdataWithRange:r2];
+    XCTAssertNotEqual([testData bytes] + offset, [subDataFromOffset bytes]);
+}
+
 #pragma mark helper
 
 - (void)assertDataByTrimmingWhiteSpacesFromTestStringUsedInFormat:(NSString *)format