MCP Java Testing Agent

This repository provides an MCP (Model Context Protocol) server that exposes tools to automate test generation, coverage analysis, and style checking for Java/Maven projects. It is designed to be driven by an MCP-aware client using the tester.prompt.md prompt.

Overview

The MCP server (in main.py) exposes tools that:

• Discover public methods in a Java codebase

• Generate skeleton JUnit tests

• Run Maven (mvn clean test)

• Analyze JaCoCo coverage reports

• Analyze Checkstyle reports

The higher-level loop (iterating until coverage/style goals are met) is described in tester.prompt.md and executed by the LLM client, not hard-coded in Python.

Requirements

• Python 3.x

• Java JDK installed and on PATH

• Maven (mvn) installed and on PATH

• Maven project configured to:

  • Place sources under something like A2/src/main/java

  • Generate JaCoCo XML at A2/target/site/jacoco/jacoco.xml

  • Generate Checkstyle XML at A2/target/checkstyle-result.xml

• An MCP-capable editor/client (e.g., VS Code with MCP integration)

Installation & Configuration

1. Clone and install:

   git clone <your-repo-url> cd <your-repo-folder> pip install fastmcp Verify: java -version mvn -v Ensure your Maven pom.xml is set up to: Run tests Produce JaCoCo and Checkstyle reports at the paths above

Running the MCP Server

From the project root:

python server.py

This starts the MCP server over SSE:

if name == "main": mcp.run(transport="sse")

Your MCP client should be configured to connect to this server. Using the tester Prompt

Assuming you’re in an editor like VS Code with MCP enabled:

The MCP client will then:

Project Structure (Typical)

├── main.py # MCP server and tools ├── .github/prompts/ │ └── tester.prompt.md # Agent configuration/prompt ├── A2/ │ ├── pom.xml │ ├── src/main/java/... # Java sources │ └── target/ │ ├── site/jacoco/jacoco.xml │ └── checkstyle-result.xml

Adjust paths as needed; defaults are used in the tool implementations. MCP Tools generate_tests(source_file: str) -> str

Generate a skeleton JUnit test class for a given .java file.

Returns: Path message on success, or an error string if the file/class/methods can’t be found. get_all_public_methods(dir: str = "A2/src/main/java") -> List[str]

Recursively scan dir for .java files and return all lines starting with public.

Returns: List of raw lines (method signatures, constructors, or public fields). analyze_coverage(xml_path: str = "A2/target/site/jacoco/jacoco.xml") -> dict

Parse a JaCoCo XML report and list methods with <100% instruction coverage.

Output structure:

{ "uncovered_methods": [ { "class": "com/example/MyClass", "method": "myMethod", "coverage": 0.75, "missed": 10, "covered": 30 }, ... ], "count": 3 }

Returns an "error" key if the XML file is missing. run_checkstyle() -> str

Run the Maven build and tests:

mvn clean test

Assumes your Maven config runs Checkstyle and JaCoCo as part of the build.

Returns: stdout from the Maven process (errors are visible in this text). analyze_checkstyle(xml_path: str = "A2/target/checkstyle-result.xml") -> dict

Parse a Checkstyle XML report and list all style violations.

Output structure:

{ "violations": [ { "file": "/path/to/Foo.java", "line": "42", "column": "13", "severity": "warning", "message": "Line is longer than 100 characters", "source": "com.puppycrawl.tools.checkstyle.checks.sizes.LineLengthCheck" }, ... ], "count": 5 }

Returns an "error" key if the XML file is missing. Agent Workflow Summary

A typical workflow implemented in tester.prompt.md:

Notes & Limitations