brick/tests/mcp_cli.rs

use brick::scan;
use serde_json::{Value, json};
use std::fs;
use std::io::Write;
use std::path::Path;
use std::process::{Command, Stdio};

fn run_mcp(model: &Path, requests: &[Value]) -> (std::process::ExitStatus, String, String) {
    let mut child = Command::new(env!("CARGO_BIN_EXE_brick"))
        .args(["mcp", model.to_str().unwrap()])
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .spawn()
        .unwrap();
    {
        let stdin = child.stdin.as_mut().unwrap();
        for request in requests {
            writeln!(stdin, "{}", serde_json::to_string(request).unwrap()).unwrap();
        }
    }
    let output = child.wait_with_output().unwrap();
    (
        output.status,
        String::from_utf8(output.stdout).unwrap(),
        String::from_utf8(output.stderr).unwrap(),
    )
}

fn responses(stdout: &str) -> Vec<Value> {
    stdout
        .lines()
        .filter(|line| !line.is_empty())
        .map(|line| serde_json::from_str(line).unwrap())
        .collect()
}

fn call(id: usize, name: &str, arguments: Value) -> Value {
    json!({
        "jsonrpc": "2.0",
        "id": id,
        "method": "tools/call",
        "params": {"name": name, "arguments": arguments}
    })
}

#[test]
fn mcp_serves_versioned_impact_cycles_bridges_and_complete_evidence() {
    let directory = tempfile::tempdir().unwrap();
    let project = directory.path().join("project");
    fs::create_dir_all(&project).unwrap();
    fs::write(
        project.join("lib.rs"),
        "fn a() { b(); }\nfn b() { a(); c(); }\nfn c() {}\n",
    )
    .unwrap();
    let model = scan::scan(&project).unwrap();
    let c_id = model
        .nodes
        .iter()
        .find(|node| node.name == "c")
        .unwrap()
        .id
        .clone();
    let bridge_id = model
        .edges
        .iter()
        .find(|edge| {
            let source = model
                .nodes
                .iter()
                .find(|node| node.id == edge.source)
                .unwrap();
            let target = model
                .nodes
                .iter()
                .find(|node| node.id == edge.target)
                .unwrap();
            source.name == "b" && target.name == "c"
        })
        .unwrap()
        .id
        .clone();
    let graph = directory.path().join("graph.json");
    fs::write(&graph, serde_json::to_vec_pretty(&model).unwrap()).unwrap();

    let requests = vec![
        json!({"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"test","version":"1"}}}),
        json!({"jsonrpc":"2.0","method":"notifications/initialized"}),
        json!({"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}),
        call(
            3,
            "brick_impact",
            json!({"node_id": c_id, "direction":"dependents", "max_depth":2}),
        ),
        call(4, "brick_cycles", json!({})),
        call(5, "brick_bridges", json!({})),
        call(6, "brick_evidence", json!({"entity_id": bridge_id})),
    ];
    let (status, stdout, stderr) = run_mcp(&graph, &requests);
    assert!(status.success(), "{stderr}");
    let messages = responses(&stdout);
    assert_eq!(messages.len(), 6);
    assert_eq!(messages[0]["result"]["protocolVersion"], "2025-06-18");
    assert_eq!(messages[1]["result"]["tools"].as_array().unwrap().len(), 6);

    let impact = &messages[2]["result"]["structuredContent"];
    assert_eq!(impact["query_schema_version"], 1);
    assert_eq!(impact["building_schema_version"], 4);
    assert_eq!(impact["impacted_nodes"].as_array().unwrap().len(), 2);

    let cycles = &messages[3]["result"]["structuredContent"];
    assert_eq!(cycles["cycles"].as_array().unwrap().len(), 1);
    assert_eq!(cycles["cycles"][0]["nodes"].as_array().unwrap().len(), 2);

    let bridges = &messages[4]["result"]["structuredContent"];
    assert!(
        bridges["bridges"]
            .as_array()
            .unwrap()
            .iter()
            .any(|entry| entry["edge"]["id"] == bridge_id)
    );

    let evidence = &messages[5]["result"]["structuredContent"];
    assert_eq!(evidence["entity_kind"], "edge");
    assert_eq!(evidence["edge"]["id"], bridge_id);
    assert_eq!(evidence["edge"]["evidence"][0]["lane"], "heuristic");
    assert_eq!(
        evidence["edge"]["evidence"][0]["backend"],
        "tree-sitter-rust:0.24.2:brick-source-v1:heuristic-resolver-v2"
    );
    assert!(evidence["edge"]["evidence"][0].get("confidence").is_some());
    assert!(evidence["edge"]["evidence"][0].get("provenance").is_some());
}

#[test]
fn mcp_enforces_initialization_lifecycle_and_required_params() {
    let directory = tempfile::tempdir().unwrap();
    fs::write(directory.path().join("lib.rs"), "fn lone() {}\n").unwrap();
    let graph = directory.path().join("graph.json");
    fs::write(
        &graph,
        serde_json::to_vec_pretty(&scan::scan(directory.path()).unwrap()).unwrap(),
    )
    .unwrap();
    let requests = vec![
        json!([]),
        json!({"jsonrpc":"2.0"}),
        json!({"jsonrpc":"2.0","id":{},"method":"ping"}),
        json!({"jsonrpc":"2.0","id":1,"method":"ping","params":[]}),
        json!({"jsonrpc":"2.0","id":"ping","method":"ping","params":{}}),
        json!({"jsonrpc":"2.0","method":"notifications/initialized","params":[]}),
        json!({"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}),
        json!({"jsonrpc":"2.0","id":3,"method":"initialize","params":{}}),
        json!({"jsonrpc":"2.0","id":4,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"test","version":"1"}}}),
        json!({"jsonrpc":"2.0","method":"notifications/initialized"}),
        json!({"jsonrpc":"2.0","id":5,"method":"tools/list","params":{}}),
    ];
    let (status, stdout, stderr) = run_mcp(&graph, &requests);
    assert!(status.success(), "{stderr}");
    let messages = responses(&stdout);
    assert_eq!(messages.len(), 9);
    for message in &messages[0..4] {
        assert_eq!(message["error"]["code"], -32600);
    }
    assert_eq!(messages[0]["id"], Value::Null);
    assert_eq!(messages[1]["id"], Value::Null);
    assert_eq!(messages[2]["id"], Value::Null);
    assert_eq!(messages[3]["id"], 1);
    assert_eq!(messages[4]["id"], "ping");
    assert_eq!(messages[4]["result"], json!({}));
    assert_eq!(messages[5]["error"]["code"], -32002);
    assert_eq!(messages[6]["error"]["code"], -32602);
    assert_eq!(messages[7]["result"]["protocolVersion"], "2025-06-18");
    assert_eq!(messages[8]["result"]["tools"].as_array().unwrap().len(), 6);
}

#[test]
fn mcp_returns_clean_negatives_and_rejects_incompatible_models() {
    let directory = tempfile::tempdir().unwrap();
    fs::write(directory.path().join("lib.rs"), "fn lone() {}\n").unwrap();
    let model = scan::scan(directory.path()).unwrap();
    let lone_id = model
        .nodes
        .iter()
        .find(|node| node.name == "lone")
        .unwrap()
        .id
        .clone();
    let graph = directory.path().join("graph.json");
    fs::write(&graph, serde_json::to_vec_pretty(&model).unwrap()).unwrap();
    let requests = vec![
        json!({"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"test","version":"1"}}}),
        json!({"jsonrpc":"2.0","method":"notifications/initialized"}),
        call(2, "brick_impact", json!({"node_id": lone_id})),
        call(3, "brick_cycles", json!({})),
        call(4, "brick_bridges", json!({})),
        call(5, "brick_evidence", json!({"entity_id":"edge:missing"})),
        call(6, "brick_cycles", json!({"unknown": true})),
        call(7, "brick_unknown", json!({})),
    ];
    let (status, stdout, stderr) = run_mcp(&graph, &requests);
    assert!(status.success(), "{stderr}");
    let messages = responses(&stdout);
    assert!(
        messages[1]["result"]["structuredContent"]["impacted_nodes"]
            .as_array()
            .unwrap()
            .is_empty()
    );
    assert!(
        messages[2]["result"]["structuredContent"]["cycles"]
            .as_array()
            .unwrap()
            .is_empty()
    );
    assert!(
        messages[3]["result"]["structuredContent"]["bridges"]
            .as_array()
            .unwrap()
            .is_empty()
    );
    assert_eq!(messages[4]["result"]["isError"], true);
    assert!(
        messages[4]["result"]["content"][0]["text"]
            .as_str()
            .unwrap()
            .contains("unknown Brick entity")
    );
    assert_eq!(messages[5]["error"]["code"], -32602);
    assert_eq!(messages[6]["error"]["code"], -32602);

    let no_requests: Vec<Value> = Vec::new();
    let mut incompatible: Value = serde_json::to_value(&model).unwrap();
    incompatible
        .as_object_mut()
        .unwrap()
        .insert("schema_version".into(), json!(3));
    let old_graph = directory.path().join("old.json");
    fs::write(
        &old_graph,
        serde_json::to_vec_pretty(&incompatible).unwrap(),
    )
    .unwrap();
    let (status, _, stderr) = run_mcp(&old_graph, &no_requests);
    assert!(!status.success());
    assert!(stderr.contains("incompatible"));

    let mut no_evidence = serde_json::to_value(model).unwrap();
    no_evidence["edges"][0]["evidence"] = json!([]);
    let no_evidence_graph = directory.path().join("no-evidence.json");
    fs::write(
        &no_evidence_graph,
        serde_json::to_vec_pretty(&no_evidence).unwrap(),
    )
    .unwrap();
    let (status, _, stderr) = run_mcp(&no_evidence_graph, &no_requests);
    assert!(!status.success());
    assert!(stderr.contains("has no evidence"));

    let mut invalid_scope = serde_json::to_value(scan::scan(directory.path()).unwrap()).unwrap();
    invalid_scope["scope"]["path"] = json!("../src");
    let invalid_scope_graph = directory.path().join("invalid-scope.json");
    fs::write(
        &invalid_scope_graph,
        serde_json::to_vec_pretty(&invalid_scope).unwrap(),
    )
    .unwrap();
    let (status, _, stderr) = run_mcp(&invalid_scope_graph, &no_requests);
    assert!(!status.success());
    assert!(stderr.contains("invalid scan scope"));
}