mbx 0.5.1

A build cache for Rust projects
Documentation 
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use super::*;

fn test_config(cache_dir: &Path) -> Config {
    Config {
        cache_dir: cache_dir.to_path_buf(),
        stats_report: None,
        verify: false,
        incremental: false,
        share_out_dir: false,
        remote: Default::default(),
        http: Default::default(),
        gc: Default::default(),
        target: crate::config::TargetSettings {
            views: false,
            root: cache_dir.join("targets"),
        },
    }
}

#[tokio::test]
async fn session_environment_directs_cargo_at_the_shim() {
    let cache = tempfile::tempdir().unwrap();
    let session_dir = tempfile::tempdir().unwrap();
    let session = CacheSession::start(session_dir.path(), &test_config(cache.path()))
        .await
        .unwrap();

    let workspace = tempfile::tempdir().unwrap();
    let mut values = BTreeMap::from([("RUSTC_WRAPPER".into(), "existing".into())]);
    let run = session
        .begin(
            workspace.path(),
            &workspace.path().join("target"),
            &["build".to_string()],
            &mut values,
        )
        .await;

    assert!(run.is_some());
    assert!(values.contains_key(SOCKET_ENV));
    assert!(values.contains_key(STAGING_ENV));
    assert_eq!(values.get(BUILD_ENV).unwrap().len(), 64);
    // The shim carries an .exe suffix on Windows, so compare stems.
    let wrapper = Path::new(values.get("RUSTC_WRAPPER").unwrap());
    assert_eq!(wrapper.file_stem().unwrap(), RUSTC_SHIM_STEM);
    assert_eq!(values.get(PREVIOUS_RUSTC_WRAPPER_ENV).unwrap(), "existing");
    assert_eq!(values.get("CARGO_INCREMENTAL").unwrap(), "0");
    assert_eq!(values.get(VERIFY_ENV).unwrap(), "0");

    session.finish().await.unwrap();
}

#[tokio::test]
async fn incremental_builds_leave_cargo_incremental_alone() {
    let cache = tempfile::tempdir().unwrap();
    let session_dir = tempfile::tempdir().unwrap();
    let mut config = test_config(cache.path());
    config.incremental = true;
    let session = CacheSession::start(session_dir.path(), &config)
        .await
        .unwrap();

    let workspace = tempfile::tempdir().unwrap();
    let mut values = BTreeMap::new();
    session
        .begin(
            workspace.path(),
            &workspace.path().join("target"),
            &["build".to_string()],
            &mut values,
        )
        .await;

    // Absent, not "1": cargo's own per-profile default is what we want, and
    // forcing the value on would turn incremental on for release too.
    assert!(!values.contains_key("CARGO_INCREMENTAL"));

    session.finish().await.unwrap();
}

#[tokio::test]
async fn verify_mode_is_passed_to_the_shim() {
    let cache = tempfile::tempdir().unwrap();
    let session_dir = tempfile::tempdir().unwrap();
    let mut config = test_config(cache.path());
    config.verify = true;
    let session = CacheSession::start(session_dir.path(), &config)
        .await
        .unwrap();

    let workspace = tempfile::tempdir().unwrap();
    let mut values = BTreeMap::new();
    session
        .begin(
            workspace.path(),
            &workspace.path().join("target"),
            &["build".to_string()],
            &mut values,
        )
        .await;

    assert_eq!(values.get(VERIFY_ENV).unwrap(), "1");

    session.finish().await.unwrap();
}

#[test]
fn identity_follows_the_dependency_graph_not_the_path() {
    let first = tempfile::tempdir().unwrap();
    let second = tempfile::tempdir().unwrap();
    std::fs::write(first.path().join("Cargo.lock"), "version = 4\n").unwrap();
    std::fs::write(second.path().join("Cargo.lock"), "version = 4\n").unwrap();
    let command = ["build".to_string()];

    assert_eq!(
        build_identity(first.path(), &command),
        build_identity(second.path(), &command),
        "separate worktrees of one project must share a manifest"
    );

    std::fs::write(second.path().join("Cargo.lock"), "version = 3\n").unwrap();
    assert_ne!(
        build_identity(first.path(), &command),
        build_identity(second.path(), &command),
    );
    assert_ne!(
        build_identity(first.path(), &command),
        build_identity(first.path(), &["test".to_string()]),
    );
}

#[test]
fn identity_falls_back_to_the_directory_name() {
    let directory = tempfile::tempdir().unwrap();
    let command = ["build".to_string()];
    assert_eq!(
        build_identity(directory.path(), &command).len(),
        64,
        "a project without a lockfile still gets an identity"
    );
}

#[test]
fn handshake_rejects_version_skew() {
    let response = serde_json::to_string(&AgentResponse::Hello {
        protocol: AGENT_PROTOCOL_VERSION,
        agent_version: "another-version".into(),
    })
    .unwrap();
    assert!(validate_handshake_response(&response).is_err());
}

/// Build the statistics a test needs without naming every counter.
///
/// `AgentStats` is `#[non_exhaustive]` so that the agent can keep adding
/// counters, which also means no struct literal can be written from here.
fn agent_stats(fill: impl FnOnce(&mut AgentStats)) -> AgentStats {
    let mut stats = AgentStats::default();
    fill(&mut stats);
    stats
}

#[test]
fn qualification_results_are_not_reported_as_misses() {
    let stats = agent_stats(|stats| {
        stats.lookups = 5;
        stats.hits = 2;
        stats.verifications = 2;
    });
    assert_eq!(cache_misses(&stats), 1);
}

#[test]
fn compiler_only_sessions_are_reportable() {
    let stats = agent_stats(|stats| {
        stats.compiler =
            BTreeMap::from([("bypass".into(), mbx_cache_core::CompilerStats::new(1, 42))]);
    });

    assert!(should_display_stats(&stats));
}

#[test]
fn a_session_that_only_failed_its_remote_is_reportable() {
    // Nothing was looked up, stored or compiled, so every other signal this
    // gate reads is zero -- and a remote cache that answered nothing but
    // failures is the one thing the build most needs to be told about.
    let stats = agent_stats(|stats| stats.remote_failures = 3);

    assert!(should_display_stats(&stats));
}

#[test]
fn writes_versioned_stats_report() {
    let directory = tempfile::tempdir().unwrap();
    let path = directory.path().join("nested").join("stats.json");
    let stats = agent_stats(|stats| {
        stats.session_duration_ns = 42;
        stats.lookups = 5;
        stats.hits = 2;
        stats.verifications = 1;
        stats.prefetched_actions = 3;
        stats.downloaded_bytes = 1024;
        stats.restored_output_files = 7;
        stats.restored_output_bytes = 2048;
        stats.reflinked_output_files = 5;
        stats.reflinked_output_bytes = 1536;
        stats.copied_output_files = 2;
        stats.copied_output_bytes = 512;
        stats.avoided_compiler_duration_ns = 2_000;
        stats.compiler =
            BTreeMap::from([("miss".into(), mbx_cache_core::CompilerStats::new(3, 4_000))]);
        stats.slow_compilations = BTreeMap::from([("slow_crate".into(), 3_000)]);
        stats.remote_blob_requests = 4;
        stats.remote_blob_pack_requests = 2;
        stats.remote_blob_pack_blobs = 100;
        stats.materialization_duration_ns = 9;
    });

    write_stats_report(&path, &stats).unwrap();
    let report: serde_json::Value = serde_json::from_slice(&std::fs::read(path).unwrap()).unwrap();

    assert_eq!(report["version"], 2);
    assert_eq!(report["session_duration_ns"], 42);
    assert_eq!(report["hits"], 2);
    assert_eq!(report["misses"], 2);
    assert_eq!(report["compiler_invocations_avoided"], 2);
    assert_eq!(report["estimated_compiler_duration_avoided_ns"], 2_000);
    assert_eq!(report["compiler"]["miss"]["invocations"], 3);
    assert_eq!(report["compiler"]["miss"]["duration_ns"], 4_000);
    assert_eq!(report["slow_compilations"][0]["crate_name"], "slow_crate");
    assert_eq!(report["slow_compilations"][0]["duration_ns"], 3_000);
    assert_eq!(report["prefetched_actions"], 3);
    assert_eq!(report["downloaded_bytes"], 1024);
    assert_eq!(report["restored_output_files"], 7);
    assert_eq!(report["restored_output_bytes"], 2048);
    assert_eq!(report["reflinked_output_files"], 5);
    assert_eq!(report["reflinked_output_bytes"], 1536);
    assert_eq!(report["copied_output_files"], 2);
    assert_eq!(report["copied_output_bytes"], 512);
    assert_eq!(report["remote_blob_requests"], 4);
    assert_eq!(report["remote_blob_pack_requests"], 2);
    assert_eq!(report["remote_blob_pack_blobs"], 100);
    assert_eq!(report["materialization_duration_ns"], 9);
}

#[test]
fn finds_crate_names_in_transparent_invocations() {
    assert_eq!(
        crate_name_argument(&["--crate-name".into(), "fixture".into()]),
        Some("fixture".into())
    );
    assert_eq!(
        crate_name_argument(&["--crate-name=attached".into()]),
        Some("attached".into())
    );
    assert_eq!(crate_name_argument(&["--version".into()]), None);
}