Anticipate reactor.test.TestSubscriber removal

reactor.test.TestSubscriber will not be part of Reactor Core
3.0.0 since it needs to be refactored to fit all the needs
expressed by the users. It is likely to be back later in one
of the Reactor Core 3.0.x releases.

This commit anticipate this removal by temporarily copying
TestSubscriber in spring-core test classes. As soon as
the new TestSubscriber will be available in Reactor Core,
Spring Framework reactive tests will use it again.

spring-core/src/test/java/org/springframework/core/codec/ByteBufferDecoderTests.java

@@ -21,11 +21,11 @@ import java.nio.ByteBuffer;
 import org.junit.Test;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
-import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.tests.TestSubscriber;
 import org.springframework.util.MimeTypeUtils;
 
 import static org.junit.Assert.assertFalse;

spring-core/src/test/java/org/springframework/core/codec/ByteBufferEncoderTests.java

@@ -23,11 +23,11 @@ import org.junit.Before;
 import org.junit.Test;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
-import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.tests.TestSubscriber;
 import org.springframework.util.MimeTypeUtils;
 
 import static org.junit.Assert.assertArrayEquals;

spring-core/src/test/java/org/springframework/core/codec/CharSequenceEncoderTests.java

@@ -21,11 +21,11 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import reactor.core.publisher.Flux;
-import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.tests.TestSubscriber;
 import org.springframework.util.MimeTypeUtils;
 
 import static org.junit.Assert.assertFalse;

spring-core/src/test/java/org/springframework/core/codec/ResourceDecoderTests.java

@@ -20,7 +20,6 @@ import java.io.IOException;
 
 import org.junit.Test;
 import reactor.core.publisher.Flux;
-import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.ByteArrayResource;
@@ -28,6 +27,7 @@ import org.springframework.core.io.InputStreamResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.tests.TestSubscriber;
 import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.StreamUtils;
 

spring-core/src/test/java/org/springframework/core/codec/ResourceEncoderTests.java

@@ -21,7 +21,6 @@ import java.nio.charset.StandardCharsets;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
-import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.ByteArrayResource;
@@ -29,6 +28,7 @@ import org.springframework.core.io.InputStreamResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.tests.TestSubscriber;
 import org.springframework.util.MimeTypeUtils;
 
 import static org.junit.Assert.assertTrue;

spring-core/src/test/java/org/springframework/core/codec/StringDecoderTests.java

@@ -19,11 +19,11 @@ package org.springframework.core.codec;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
-import reactor.test.TestSubscriber;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.tests.TestSubscriber;
 import org.springframework.util.MimeTypeUtils;
 
 import static org.junit.Assert.assertFalse;

spring-core/src/test/java/org/springframework/core/io/buffer/DataBufferUtilsTests.java

@@ -24,7 +24,7 @@ import java.nio.file.StandardOpenOption;
 
 import org.junit.Test;
 import reactor.core.publisher.Flux;
-import reactor.test.TestSubscriber;
+import org.springframework.tests.TestSubscriber;
 
 import static org.junit.Assert.*;