test: Add comprehensive JUnit 5 unit tests for HttpMcpToolboxClient

src/test/java/com/google/cloud/mcp/HttpMcpToolboxClientTest.java

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+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.cloud.mcp;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.lang.reflect.Field;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+
+class HttpMcpToolboxClientTest {
+
+  private HttpMcpToolboxClient client;
+  private HttpClient mockHttpClient;
+  private ObjectMapper objectMapper = new ObjectMapper();
+
+  @BeforeEach
+  @SuppressWarnings("unchecked")
+  void setUp() throws Exception {
+    client = new HttpMcpToolboxClient("http://localhost:8080", "test-api-key");
+    mockHttpClient = mock(HttpClient.class);
+
+    // Inject mock HttpClient using reflection
+    Field httpClientField = HttpMcpToolboxClient.class.getDeclaredField("httpClient");
+    httpClientField.setAccessible(true);
+    httpClientField.set(client, mockHttpClient);
+  }
+
+  @Test
+  void testEnsureInitializedCalledOnce() throws Exception {
+    // Setup mock responses
+    HttpResponse<String> initResponse = mock(HttpResponse.class);
+    when(initResponse.statusCode()).thenReturn(200);
+    when(initResponse.body()).thenReturn("{}");
+
+    HttpResponse<String> notifResponse = mock(HttpResponse.class);
+    when(notifResponse.statusCode()).thenReturn(200);
+    when(notifResponse.body()).thenReturn("{}");
+
+    HttpResponse<String> listResponse = mock(HttpResponse.class);
+    when(listResponse.statusCode()).thenReturn(200);
+    when(listResponse.body())
+        .thenReturn(
+            "{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":{\"tools\":[{\"name\":\"test-tool\","
+                + "\"description\":\"A test tool\",\"inputSchema\":{\"type\":\"object\","
+                + "\"properties\":{\"param1\":{\"type\":\"string\"}},"
+                + "\"required\":[\"param1\"]}}]}}");
+
+    // The order of requests will be: initialize, notifications/initialized, tools/list
+    when(mockHttpClient.sendAsync(any(HttpRequest.class), any(HttpResponse.BodyHandler.class)))
+        .thenReturn(CompletableFuture.completedFuture(initResponse))
+        .thenReturn(CompletableFuture.completedFuture(notifResponse))
+        .thenReturn(CompletableFuture.completedFuture(listResponse))
+        .thenReturn(CompletableFuture.completedFuture(listResponse));
+
+    // Call listTools multiple times
+    client.listTools().join();
+    client.listTools().join();
+
+    // Verify requests
+    ArgumentCaptor<HttpRequest> requestCaptor = ArgumentCaptor.forClass(HttpRequest.class);
+    verify(mockHttpClient, times(4)).sendAsync(requestCaptor.capture(), any());
+
+    long initCount = requestCaptor.getAllValues().stream()
+        .filter(req -> getBodyStringQuietly(req).contains("\"method\":\"initialize\""))
+        .count();
+    long notifCount =
+        requestCaptor.getAllValues().stream()
+            .filter(
+                req ->
+                    getBodyStringQuietly(req).contains("\"method\":\"notifications/initialized\""))
+            .count();
+    long listCount = requestCaptor.getAllValues().stream()
+        .filter(req -> getBodyStringQuietly(req).contains("\"method\":\"tools/list\""))
+        .count();
+
+    assertEquals(1, initCount, "initialize should be called exactly once");
+    assertEquals(1, notifCount, "notifications/initialized should be called exactly once");
+    assertEquals(2, listCount, "tools/list should be called twice");
+  }
+
+  @Test
+  void testListTools() throws Exception {
+    // Setup mock responses
+    HttpResponse<String> initResponse = mock(HttpResponse.class);
+    when(initResponse.statusCode()).thenReturn(200);
+    when(initResponse.body()).thenReturn("{}");
+
+    HttpResponse<String> notifResponse = mock(HttpResponse.class);
+    when(notifResponse.statusCode()).thenReturn(200);
+    when(notifResponse.body()).thenReturn("{}");
+
+    String listBody =
+        "{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":{\"tools\":[{\"name\":\"test-tool\","
+            + "\"description\":\"A test tool\",\"inputSchema\":{\"type\":\"object\","
+            + "\"properties\":{\"param1\":{\"type\":\"string\",\"description\":\"param desc\"}},"
+            + "\"required\":[\"param1\"]},\"_meta\":{\"toolbox/authInvoke\":[\"auth1\"]}}]}}";
+    HttpResponse<String> listResponse = mock(HttpResponse.class);
+    when(listResponse.statusCode()).thenReturn(200);
+    when(listResponse.body()).thenReturn(listBody);
+
+    when(mockHttpClient.sendAsync(any(HttpRequest.class), any(HttpResponse.BodyHandler.class)))
+        .thenReturn(CompletableFuture.completedFuture(initResponse))
+        .thenReturn(CompletableFuture.completedFuture(notifResponse))
+        .thenReturn(CompletableFuture.completedFuture(listResponse));
+
+    Map<String, ToolDefinition> tools = client.listTools().join();
+
+    assertNotNull(tools);
+    assertEquals(1, tools.size());
+    assertTrue(tools.containsKey("test-tool"));
+
+    ToolDefinition toolDef = tools.get("test-tool");
+    assertEquals("A test tool", toolDef.description());
+    assertEquals(1, toolDef.authRequired().size());
+    assertEquals("auth1", toolDef.authRequired().get(0));
+
+    assertEquals(1, toolDef.parameters().size());
+    ToolDefinition.Parameter param = toolDef.parameters().get(0);
+    assertEquals("param1", param.name());
+    assertEquals("string", param.type());
+    assertEquals("param desc", param.description());
+    assertTrue(param.required());
+  }
+
+  @Test
+  void testInvokeTool() throws Exception {
+    // Setup mock responses
+    HttpResponse<String> initResponse = mock(HttpResponse.class);
+    when(initResponse.statusCode()).thenReturn(200);
+    when(initResponse.body()).thenReturn("{}");
+
+    HttpResponse<String> notifResponse = mock(HttpResponse.class);
+    when(notifResponse.statusCode()).thenReturn(200);
+    when(notifResponse.body()).thenReturn("{}");
+
+    String callBody =
+        "{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":{\"content\":[{\"type\":\"text\","
+            + "\"text\":\"success\"}],\"isError\":false}}";
+    HttpResponse<String> callResponse = mock(HttpResponse.class);
+    when(callResponse.statusCode()).thenReturn(200);
+    when(callResponse.body()).thenReturn(callBody);
+
+    when(mockHttpClient.sendAsync(any(HttpRequest.class), any(HttpResponse.BodyHandler.class)))
+        .thenReturn(CompletableFuture.completedFuture(initResponse))
+        .thenReturn(CompletableFuture.completedFuture(notifResponse))
+        .thenReturn(CompletableFuture.completedFuture(callResponse));
+
+    ToolResult result = client.invokeTool("test-tool", Map.of("param1", "value1")).join();
+
+    assertNotNull(result);
+    assertFalse(result.isError());
+    assertEquals(1, result.content().size());
+    assertEquals("success", result.content().get(0).text());
+
+    // Verify request payload
+    ArgumentCaptor<HttpRequest> requestCaptor = ArgumentCaptor.forClass(HttpRequest.class);
+    verify(mockHttpClient, times(3)).sendAsync(requestCaptor.capture(), any());
+
+    HttpRequest callReq = requestCaptor.getAllValues().get(2);
+    String bodyStr = getBodyString(callReq);
+
+    JsonNode root = objectMapper.readTree(bodyStr);
+    assertEquals("tools/call", root.get("method").asText());
+    JsonNode params = root.get("params");
+    assertEquals("test-tool", params.get("name").asText());
+    assertEquals("value1", params.get("arguments").get("param1").asText());
+  }
+
+  private String getBodyStringQuietly(HttpRequest request) {
+    try {
+      return getBodyString(request);
+    } catch (Exception e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private String getBodyString(HttpRequest request) throws Exception {
+    if (request.bodyPublisher().isPresent()) {
+      var publisher = request.bodyPublisher().get();
+      var subscriber =
+          HttpResponse.BodySubscribers.ofString(java.nio.charset.StandardCharsets.UTF_8);
+      publisher.subscribe(new java.util.concurrent.Flow.Subscriber<java.nio.ByteBuffer>() {
+        @Override
+        public void onSubscribe(java.util.concurrent.Flow.Subscription subscription) {
+          subscriber.onSubscribe(subscription);
+          subscription.request(Long.MAX_VALUE);
+        }
+
+        @Override
+        public void onNext(java.nio.ByteBuffer item) {
+          subscriber.onNext(java.util.List.of(item));
+        }
+
+        @Override
+        public void onError(Throwable throwable) {
+          subscriber.onError(throwable);
+        }
+
+        @Override
+        public void onComplete() {
+          subscriber.onComplete();
+        }
+      });
+      return subscriber.getBody().toCompletableFuture().join();
+    }
+    return "";
+  }
+}