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| 1 | +/* |
| 2 | + * Copyright 2024-2024 the original author or authors. |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * https://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +package org.springframework.ai.mcp.client; |
| 18 | + |
| 19 | +import java.time.Duration; |
| 20 | +import java.util.List; |
| 21 | + |
| 22 | +import org.junit.jupiter.api.Test; |
| 23 | +import reactor.core.publisher.Mono; |
| 24 | +import reactor.test.StepVerifier; |
| 25 | + |
| 26 | +import org.springframework.ai.mcp.MockMcpTransport; |
| 27 | +import org.springframework.ai.mcp.spec.McpError; |
| 28 | +import org.springframework.ai.mcp.spec.McpSchema; |
| 29 | +import org.springframework.ai.mcp.spec.McpSchema.InitializeResult; |
| 30 | + |
| 31 | +import static org.assertj.core.api.Assertions.assertThat; |
| 32 | + |
| 33 | +/** |
| 34 | + * Tests for MCP protocol version negotiation and compatibility. |
| 35 | + */ |
| 36 | +class McpClientProtocolVersionTests { |
| 37 | + |
| 38 | + private static final Duration REQUEST_TIMEOUT = Duration.ofSeconds(30); |
| 39 | + |
| 40 | + private static final McpSchema.Implementation CLIENT_INFO = new McpSchema.Implementation("test-client", "1.0.0"); |
| 41 | + |
| 42 | + @Test |
| 43 | + void shouldUseLatestVersionByDefault() { |
| 44 | + MockMcpTransport transport = new MockMcpTransport(); |
| 45 | + McpAsyncClient client = McpClient.async(transport) |
| 46 | + .clientInfo(CLIENT_INFO) |
| 47 | + .requestTimeout(REQUEST_TIMEOUT) |
| 48 | + .build(); |
| 49 | + |
| 50 | + try { |
| 51 | + Mono<InitializeResult> initializeResultMono = client.initialize(); |
| 52 | + |
| 53 | + StepVerifier.create(initializeResultMono).then(() -> { |
| 54 | + McpSchema.JSONRPCRequest request = transport.getLastSentMessageAsRequest(); |
| 55 | + assertThat(request.params()).isInstanceOf(McpSchema.InitializeRequest.class); |
| 56 | + McpSchema.InitializeRequest initRequest = (McpSchema.InitializeRequest) request.params(); |
| 57 | + assertThat(initRequest.protocolVersion()).isEqualTo(McpSchema.LATEST_PROTOCOL_VERSION); |
| 58 | + |
| 59 | + transport.simulateIncomingMessage(new McpSchema.JSONRPCResponse(McpSchema.JSONRPC_VERSION, request.id(), |
| 60 | + new McpSchema.InitializeResult(McpSchema.LATEST_PROTOCOL_VERSION, null, |
| 61 | + new McpSchema.Implementation("test-server", "1.0.0"), null), |
| 62 | + null)); |
| 63 | + }).assertNext(result -> { |
| 64 | + assertThat(result.protocolVersion()).isEqualTo(McpSchema.LATEST_PROTOCOL_VERSION); |
| 65 | + }).verifyComplete(); |
| 66 | + |
| 67 | + } |
| 68 | + finally { |
| 69 | + // Ensure cleanup happens even if test fails |
| 70 | + StepVerifier.create(client.closeGracefully()).verifyComplete(); |
| 71 | + } |
| 72 | + } |
| 73 | + |
| 74 | + @Test |
| 75 | + void shouldNegotiateSpecificVersion() { |
| 76 | + String oldVersion = "0.1.0"; |
| 77 | + MockMcpTransport transport = new MockMcpTransport(); |
| 78 | + McpAsyncClient client = McpClient.async(transport) |
| 79 | + .clientInfo(CLIENT_INFO) |
| 80 | + .requestTimeout(REQUEST_TIMEOUT) |
| 81 | + .build(); |
| 82 | + |
| 83 | + client.setProtocolVersions(List.of(oldVersion, McpSchema.LATEST_PROTOCOL_VERSION)); |
| 84 | + |
| 85 | + try { |
| 86 | + Mono<InitializeResult> initializeResultMono = client.initialize(); |
| 87 | + |
| 88 | + StepVerifier.create(initializeResultMono).then(() -> { |
| 89 | + McpSchema.JSONRPCRequest request = transport.getLastSentMessageAsRequest(); |
| 90 | + assertThat(request.params()).isInstanceOf(McpSchema.InitializeRequest.class); |
| 91 | + McpSchema.InitializeRequest initRequest = (McpSchema.InitializeRequest) request.params(); |
| 92 | + assertThat(initRequest.protocolVersion()).isIn(List.of(oldVersion, McpSchema.LATEST_PROTOCOL_VERSION)); |
| 93 | + |
| 94 | + transport.simulateIncomingMessage(new McpSchema.JSONRPCResponse(McpSchema.JSONRPC_VERSION, request.id(), |
| 95 | + new McpSchema.InitializeResult(oldVersion, null, |
| 96 | + new McpSchema.Implementation("test-server", "1.0.0"), null), |
| 97 | + null)); |
| 98 | + }).assertNext(result -> { |
| 99 | + assertThat(result.protocolVersion()).isEqualTo(oldVersion); |
| 100 | + }).verifyComplete(); |
| 101 | + } |
| 102 | + finally { |
| 103 | + StepVerifier.create(client.closeGracefully()).verifyComplete(); |
| 104 | + } |
| 105 | + } |
| 106 | + |
| 107 | + @Test |
| 108 | + void shouldFailForUnsupportedVersion() { |
| 109 | + String unsupportedVersion = "999.999.999"; |
| 110 | + MockMcpTransport transport = new MockMcpTransport(); |
| 111 | + McpAsyncClient client = McpClient.async(transport) |
| 112 | + .clientInfo(CLIENT_INFO) |
| 113 | + .requestTimeout(REQUEST_TIMEOUT) |
| 114 | + .build(); |
| 115 | + |
| 116 | + try { |
| 117 | + Mono<InitializeResult> initializeResultMono = client.initialize(); |
| 118 | + |
| 119 | + StepVerifier.create(initializeResultMono).then(() -> { |
| 120 | + McpSchema.JSONRPCRequest request = transport.getLastSentMessageAsRequest(); |
| 121 | + assertThat(request.params()).isInstanceOf(McpSchema.InitializeRequest.class); |
| 122 | + |
| 123 | + transport.simulateIncomingMessage(new McpSchema.JSONRPCResponse(McpSchema.JSONRPC_VERSION, request.id(), |
| 124 | + new McpSchema.InitializeResult(unsupportedVersion, null, |
| 125 | + new McpSchema.Implementation("test-server", "1.0.0"), null), |
| 126 | + null)); |
| 127 | + }).expectError(McpError.class).verify(); |
| 128 | + } |
| 129 | + finally { |
| 130 | + StepVerifier.create(client.closeGracefully()).verifyComplete(); |
| 131 | + } |
| 132 | + } |
| 133 | + |
| 134 | + @Test |
| 135 | + void shouldUseHighestVersionWhenMultipleSupported() { |
| 136 | + String oldVersion = "0.1.0"; |
| 137 | + String middleVersion = "0.2.0"; |
| 138 | + String latestVersion = McpSchema.LATEST_PROTOCOL_VERSION; |
| 139 | + |
| 140 | + MockMcpTransport transport = new MockMcpTransport(); |
| 141 | + McpAsyncClient client = McpClient.async(transport) |
| 142 | + .clientInfo(CLIENT_INFO) |
| 143 | + .requestTimeout(REQUEST_TIMEOUT) |
| 144 | + .build(); |
| 145 | + |
| 146 | + client.setProtocolVersions(List.of(oldVersion, middleVersion, latestVersion)); |
| 147 | + |
| 148 | + try { |
| 149 | + Mono<InitializeResult> initializeResultMono = client.initialize(); |
| 150 | + |
| 151 | + StepVerifier.create(initializeResultMono).then(() -> { |
| 152 | + McpSchema.JSONRPCRequest request = transport.getLastSentMessageAsRequest(); |
| 153 | + McpSchema.InitializeRequest initRequest = (McpSchema.InitializeRequest) request.params(); |
| 154 | + assertThat(initRequest.protocolVersion()).isEqualTo(latestVersion); |
| 155 | + |
| 156 | + transport.simulateIncomingMessage(new McpSchema.JSONRPCResponse(McpSchema.JSONRPC_VERSION, request.id(), |
| 157 | + new McpSchema.InitializeResult(latestVersion, null, |
| 158 | + new McpSchema.Implementation("test-server", "1.0.0"), null), |
| 159 | + null)); |
| 160 | + }).assertNext(result -> { |
| 161 | + assertThat(result.protocolVersion()).isEqualTo(latestVersion); |
| 162 | + }).verifyComplete(); |
| 163 | + } |
| 164 | + finally { |
| 165 | + StepVerifier.create(client.closeGracefully()).verifyComplete(); |
| 166 | + } |
| 167 | + |
| 168 | + } |
| 169 | + |
| 170 | +} |
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