Module mcp 

Fluent builder for mocking an MCP (Model Context Protocol) server.

This is an idiomatic Rust port of the Java/Node/Python client McpMockBuilder (org.mockserver.client.McpMockBuilder). It produces the same wire-level expectation JSON: a set of HTTP expectations that emulate a Streamable-HTTP MCP server speaking JSON-RPC 2.0.

Each generated expectation matches a JSON-RPC method (initialize, ping, notifications/initialized, tools/list, tools/call, resources/list, resources/read, prompts/list, prompts/get) on POST <path> and responds with a Velocity template that echoes back the incoming JSON-RPC id via $!{request.jsonRpcRawId}.

Example

use mockserver_client::mcp::mcp_mock;

let expectations = mcp_mock("/mcp")
    .with_tool("get_weather")
        .with_description("Get the weather for a city")
        .with_input_schema("{\"type\":\"object\"}")
        .responding_with("sunny", false)
        .and()
    .build();

// initialize, ping, notifications/initialized, tools/list, tools/call
assert_eq!(expectations.len(), 5);

Structs

McpMockBuilder

Fluent builder producing the expectations for a mocked MCP server.

McpPromptBuilder

Sub-builder for a single MCP prompt. Call and to return to the parent McpMockBuilder.

McpResourceBuilder

Sub-builder for a single MCP resource. Call and to return to the parent McpMockBuilder.

McpToolBuilder

Sub-builder for a single MCP tool. Call and to return to the parent McpMockBuilder.

Functions

escape_json

JSON-escape a string for inlining inside a JSON string literal, returning the contents WITHOUT the surrounding quotes. Mirrors Java’s OBJECT_MAPPER.writeValueAsString(value) then stripping the outer quotes.

escape_json_path

Escape single quotes for safe inclusion inside a JSONPath string literal. Mirrors Java’s escapeJsonPath.

escape_velocity

Escape Velocity meta-characters so literal $ / # in mock content are not interpreted as Velocity references/directives. Mirrors Java: replace("$", "${esc.d}").replace("#", "${esc.h}").

mcp_mock

Create a new MCP mock builder. path defaults to /mcp if you use mcp_mock_default.

mcp_mock_default

Create a new MCP mock builder targeting the default /mcp path.

validate_and_serialize_json

Validate that the supplied string is valid JSON and return it re-serialised in compact form. Mirrors Java’s validateAndSerializeJson.