BAEL-5301 Retrying Feign Calls

feign/src/test/java/com/baeldung/feign/retry/Custom5xxErrorDecoderUnitTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.feign.retry;
+
+import feign.*;
+import feign.codec.ErrorDecoder;
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import java.nio.charset.Charset;
+import java.util.Collection;
+import java.util.HashMap;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class Custom5xxErrorDecoderUnitTest {
+    @Test
+    public void given5xxResponse_whenDecode_thenReturnRetryableException() {
+        // given
+        ErrorDecoder decoder = new Custom5xxErrorDecoder();
+        Response response = responseStub(500);
+
+        // when
+        Exception exception = decoder.decode("GET", response);
+
+        // then
+        assertTrue(exception instanceof RetryableException);
+    }
+
+    @Test
+    public void given4xxResponse_whenDecode_thenReturnFeignException() {
+        // given
+        ErrorDecoder decoder = new Custom5xxErrorDecoder();
+        Response response = responseStub(400);
+
+        // when
+        Exception exception = decoder.decode("GET", response);
+
+        // then
+        assertTrue(exception instanceof FeignException);
+        assertFalse(exception instanceof RetryableException);
+    }
+
+    @NotNull
+    private Response responseStub(int status) {
+        return Response.builder()
+                .request(Request.create(
+                        Request.HttpMethod.GET, "url", new HashMap<String, Collection<String>>(), new byte[0], Charset.defaultCharset(), new RequestTemplate()))
+                .status(status)
+                .build();
+    }
+}