From c5694dc2b7f095a88a3d6d8cb88f069f8a10a56b Mon Sep 17 00:00:00 2001
From: Mikhail Polivakha <68962645+Mikhail2048@users.noreply.github.com>
Date: Mon, 27 Mar 2023 18:52:56 +0300
Subject: [PATCH] misha2048 Retrying Requests using Apache HttpClient (#13712)

---
 .../ApacheHttpClientRetryIntegrationTest.java | 168 ++++++++++++++++++
 1 file changed, 168 insertions(+)
 create mode 100644 apache-httpclient4/src/test/java/com/baeldung/httpclient/retry/ApacheHttpClientRetryIntegrationTest.java

diff --git a/apache-httpclient4/src/test/java/com/baeldung/httpclient/retry/ApacheHttpClientRetryIntegrationTest.java b/apache-httpclient4/src/test/java/com/baeldung/httpclient/retry/ApacheHttpClientRetryIntegrationTest.java
new file mode 100644
index 0000000000..cfb51f058a
--- /dev/null
+++ b/apache-httpclient4/src/test/java/com/baeldung/httpclient/retry/ApacheHttpClientRetryIntegrationTest.java
@@ -0,0 +1,168 @@
+package com.baeldung.httpclient.retry;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.UnknownHostException;
+import java.util.Objects;
+
+import org.apache.http.HttpRequestInterceptor;
+import org.apache.http.HttpResponseInterceptor;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.methods.HttpPatch;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.client.methods.HttpPut;
+import org.apache.http.client.protocol.HttpClientContext;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
+import org.apache.http.impl.client.HttpClientBuilder;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class ApacheHttpClientRetryIntegrationTest {
+
+    private Integer requestCounter;
+    private CloseableHttpClient httpClient;
+
+    @BeforeEach
+    void setUp() {
+        requestCounter = 0;
+    }
+
+    @AfterEach
+    void tearDown() throws IOException {
+        if (httpClient != null) {
+            httpClient.close();
+        }
+    }
+
+    private void createDefaultApacheHttpClient() {
+        this.httpClient = HttpClientBuilder
+          .create()
+          .addInterceptorFirst((HttpRequestInterceptor) (httpRequest, httpContext) -> {
+              requestCounter++;
+          }).build();
+    }
+
+    private void createFailingHttpClient() {
+        this.httpClient = HttpClientBuilder
+          .create()
+          .addInterceptorFirst((HttpRequestInterceptor) (httpRequest, httpContext) -> requestCounter++)
+          .addInterceptorLast((HttpResponseInterceptor) (httpResponse, httpContext) -> {
+              throw new IOException();
+          })
+          .build();
+    }
+
+    private void createHttpClientWithRetryHandler() {
+        this.httpClient = HttpClientBuilder
+          .create()
+          .addInterceptorFirst((HttpRequestInterceptor) (httpRequest, httpContext) -> requestCounter++)
+          .addInterceptorLast((HttpResponseInterceptor) (httpRequest, httpContext) -> { throw new IOException(); })
+          .setRetryHandler(new DefaultHttpRequestRetryHandler(6, true))
+          .build();
+    }
+
+    private void createHttpClientWithCustomRetryHandler() {
+        this.httpClient = HttpClientBuilder
+          .create()
+          .addInterceptorFirst((HttpRequestInterceptor) (httpRequest, httpContext) -> requestCounter++)
+          .addInterceptorLast((HttpResponseInterceptor) (httpRequest, httpContext) -> { throw new IOException(); })
+          .setRetryHandler((exception, executionCount, context) -> {
+              if (executionCount < 5 && Objects.equals("GET", ((HttpClientContext) context).getRequest().getRequestLine().getMethod())) {
+                  return true;
+              } else {
+                  return false;
+              }
+          })
+          .build();
+    }
+
+    private void createHttpClientWithRetriesDisabled() {
+        this.httpClient = HttpClientBuilder
+          .create()
+          .addInterceptorFirst((HttpRequestInterceptor) (httpRequest, httpContext) -> requestCounter++)
+          .addInterceptorLast((HttpResponseInterceptor) (httpRequest, httpContext) -> { throw new IOException(); })
+          .disableAutomaticRetries()
+          .build();
+    }
+
+    @Test
+    public void givenDefaultConfiguration_whenReceivedIOException_thenRetriesPerformed() {
+        createFailingHttpClient();
+        assertThrows(IOException.class, () -> httpClient.execute(new HttpGet("https://httpstat.us/200")));
+        assertThat(requestCounter).isEqualTo(4);
+    }
+
+    @Test
+    public void givenDefaultConfiguration_whenDomainNameNotResolved_thenNoRetryApplied() {
+        createDefaultApacheHttpClient();
+        HttpGet request = new HttpGet(URI.create("http://domain.that.does.not.exist:80/api/v1"));
+
+        assertThrows(UnknownHostException.class, () -> httpClient.execute(request));
+        assertThat(requestCounter).isEqualTo(1);
+    }
+
+    @Test
+    public void givenDefaultConfiguration_whenGotInternalServerError_thenNoRetryLogicApplied() throws IOException {
+        createDefaultApacheHttpClient();
+        HttpGet request = new HttpGet(URI.create("https://httpstat.us/500"));
+
+        CloseableHttpResponse response = assertDoesNotThrow(() -> httpClient.execute(request));
+        assertThat(response.getStatusLine().getStatusCode()).isEqualTo(500);
+        assertThat(requestCounter).isEqualTo(1);
+        response.close();
+    }
+
+    @Test
+    public void givenDefaultConfiguration_whenHttpPatchRequest_thenRetryIsNotApplied() {
+        createFailingHttpClient();
+        HttpPatch request = new HttpPatch(URI.create("https://httpstat.us/500"));
+
+        assertThrows(IOException.class, () -> httpClient.execute(request));
+        assertThat(requestCounter).isEqualTo(1);
+    }
+
+    @Test
+    public void givenDefaultConfiguration_whenHttpPutRequest_thenRetryIsNotApplied() {
+        createFailingHttpClient();
+        HttpPut request = new HttpPut(URI.create("https://httpstat.us/500"));
+
+        assertThrows(IOException.class, () -> httpClient.execute(request));
+        assertThat(requestCounter).isEqualTo(1);
+    }
+
+    @Test
+    public void givenConfiguredRetryHandler_whenHttpPostRequest_thenRetriesPerformed() {
+        createHttpClientWithRetryHandler();
+
+        HttpPost request = new HttpPost(URI.create("https://httpstat.us/200"));
+
+        assertThrows(IOException.class, () -> httpClient.execute(request));
+        assertThat(requestCounter).isEqualTo(7);
+    }
+
+    @Test
+    public void givenCustomRetryHandler_whenUnknownHostException_thenRetryAnyway() {
+        createHttpClientWithCustomRetryHandler();
+
+        HttpGet request = new HttpGet(URI.create("https://domain.that.does.not.exist/200"));
+
+        assertThrows(IOException.class, () -> httpClient.execute(request));
+        assertThat(requestCounter).isEqualTo(5);
+    }
+
+    @Test
+    public void givenDisabledRetries_whenExecutedHttpRequestEndUpWithIOException_thenRetryIsNotApplied() {
+        createHttpClientWithRetriesDisabled();
+        HttpGet request = new HttpGet(URI.create("https://httpstat.us/200"));
+
+        assertThrows(IOException.class, () -> httpClient.execute(request));
+        assertThat(requestCounter).isEqualTo(1);
+    }
+}