// Copyright (c) The nextest Contributors
// SPDX-License-Identifier: MIT OR Apache-2.0

use super::{DisplayFilterMatcher, TestListDisplayFilter};
use crate::{
    cargo_config::EnvironmentMap,
    double_spawn::DoubleSpawnInfo,
    errors::{CreateTestListError, FromMessagesError, WriteTestListError},
    helpers::{convert_build_platform, dylib_path, dylib_path_envvar, write_test_name},
    indenter::indented,
    list::{BinaryList, OutputFormat, RustBuildMeta, Styles, TestListState},
    reuse_build::PathMapper,
    target_runner::{PlatformRunner, TargetRunner},
    test_command::{LocalExecuteContext, TestCommand},
    test_filter::{BinaryMismatchReason, FilterBinaryMatch, FilterBound, TestFilterBuilder},
    write_str::WriteStr,
};
use camino::{Utf8Path, Utf8PathBuf};
use futures::prelude::*;
use guppy::{
    graph::{PackageGraph, PackageMetadata},
    PackageId,
};
use nextest_filtering::{BinaryQuery, EvalContext, TestQuery};
use nextest_metadata::{
    BuildPlatform, FilterMatch, MismatchReason, RustBinaryId, RustNonTestBinaryKind,
    RustTestBinaryKind, RustTestBinarySummary, RustTestCaseSummary, RustTestSuiteStatusSummary,
    RustTestSuiteSummary, TestListSummary,
};
use owo_colors::OwoColorize;
use std::{
    collections::{BTreeMap, BTreeSet},
    ffi::{OsStr, OsString},
    io,
    path::PathBuf,
    sync::{Arc, OnceLock},
};
use tokio::runtime::Runtime;
use tracing::debug;

/// A Rust test binary built by Cargo. This artifact hasn't been run yet so there's no information
/// about the tests within it.
///
/// Accepted as input to [`TestList::new`].
#[derive(Clone, Debug)]
pub struct RustTestArtifact<'g> {
    /// A unique identifier for this test artifact.
    pub binary_id: RustBinaryId,

    /// Metadata for the package this artifact is a part of. This is used to set the correct
    /// environment variables.
    pub package: PackageMetadata<'g>,

    /// The path to the binary artifact.
    pub binary_path: Utf8PathBuf,

    /// The unique binary name defined in `Cargo.toml` or inferred by the filename.
    pub binary_name: String,

    /// The kind of Rust test binary this is.
    pub kind: RustTestBinaryKind,

    /// Non-test binaries to be exposed to this artifact at runtime (name, path).
    pub non_test_binaries: BTreeSet<(String, Utf8PathBuf)>,

    /// The working directory that this test should be executed in.
    pub cwd: Utf8PathBuf,

    /// The platform for which this test artifact was built.
    pub build_platform: BuildPlatform,
}

impl<'g> RustTestArtifact<'g> {
    /// Constructs a list of test binaries from the list of built binaries.
    pub fn from_binary_list(
        graph: &'g PackageGraph,
        binary_list: Arc<BinaryList>,
        rust_build_meta: &RustBuildMeta<TestListState>,
        path_mapper: &PathMapper,
        platform_filter: Option<BuildPlatform>,
    ) -> Result<Vec<Self>, FromMessagesError> {
        let mut binaries = vec![];

        for binary in &binary_list.rust_binaries {
            if platform_filter.is_some() && platform_filter != Some(binary.build_platform) {
                continue;
            }

            // Look up the executable by package ID.
            let package_id = PackageId::new(binary.package_id.clone());
            let package = graph
                .metadata(&package_id)
                .map_err(FromMessagesError::PackageGraph)?;

            // Tests are run in the directory containing Cargo.toml
            let cwd = package
                .manifest_path()
                .parent()
                .unwrap_or_else(|| {
                    panic!(
                        "manifest path {} doesn't have a parent",
                        package.manifest_path()
                    )
                })
                .to_path_buf();

            let binary_path = path_mapper.map_binary(binary.path.clone());
            let cwd = path_mapper.map_cwd(cwd);

            // Non-test binaries are only exposed to integration tests and benchmarks.
            let non_test_binaries = if binary.kind == RustTestBinaryKind::TEST
                || binary.kind == RustTestBinaryKind::BENCH
            {
                // Note we must use the TestListState rust_build_meta here to ensure we get remapped
                // paths.
                match rust_build_meta.non_test_binaries.get(package_id.repr()) {
                    Some(binaries) => binaries
                        .iter()
                        .filter(|binary| {
                            // Only expose BIN_EXE non-test files.
                            binary.kind == RustNonTestBinaryKind::BIN_EXE
                        })
                        .map(|binary| {
                            // Convert relative paths to absolute ones by joining with the target directory.
                            let abs_path = rust_build_meta.target_directory.join(&binary.path);
                            (binary.name.clone(), abs_path)
                        })
                        .collect(),
                    None => BTreeSet::new(),
                }
            } else {
                BTreeSet::new()
            };

            binaries.push(RustTestArtifact {
                binary_id: binary.id.clone(),
                package,
                binary_path,
                binary_name: binary.name.clone(),
                kind: binary.kind.clone(),
                cwd,
                non_test_binaries,
                build_platform: binary.build_platform,
            })
        }

        Ok(binaries)
    }

    /// Returns a [`BinaryQuery`] corresponding to this test artifact.
    pub fn to_binary_query(&self) -> BinaryQuery<'_> {
        BinaryQuery {
            package_id: self.package.id(),
            binary_id: &self.binary_id,
            kind: &self.kind,
            binary_name: &self.binary_name,
            platform: convert_build_platform(self.build_platform),
        }
    }

    // ---
    // Helper methods
    // ---
    fn into_test_suite(self, status: RustTestSuiteStatus) -> (RustBinaryId, RustTestSuite<'g>) {
        let Self {
            binary_id,
            package,
            binary_path,
            binary_name,
            kind,
            non_test_binaries,
            cwd,
            build_platform,
        } = self;
        (
            binary_id.clone(),
            RustTestSuite {
                binary_id,
                binary_path,
                package,
                binary_name,
                kind,
                non_test_binaries,
                cwd,
                build_platform,
                status,
            },
        )
    }
}

/// Information about skipped tests and binaries.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SkipCounts {
    /// The number of skipped tests.
    pub skipped_tests: usize,

    /// The number of tests skipped due to not being in the default set.
    pub skipped_tests_default_filter: usize,

    /// The number of skipped binaries.
    pub skipped_binaries: usize,

    /// The number of binaries skipped due to not being in the default set.
    pub skipped_binaries_default_filter: usize,
}

/// List of test instances, obtained by querying the [`RustTestArtifact`] instances generated by Cargo.
#[derive(Clone, Debug)]
pub struct TestList<'g> {
    test_count: usize,
    rust_build_meta: RustBuildMeta<TestListState>,
    rust_suites: BTreeMap<RustBinaryId, RustTestSuite<'g>>,
    workspace_root: Utf8PathBuf,
    env: EnvironmentMap,
    updated_dylib_path: OsString,
    // Computed on first access.
    skip_counts: OnceLock<SkipCounts>,
}

impl<'g> TestList<'g> {
    /// Creates a new test list by running the given command and applying the specified filter.
    #[allow(clippy::too_many_arguments)]
    pub fn new<I>(
        ctx: &TestExecuteContext<'_>,
        test_artifacts: I,
        rust_build_meta: RustBuildMeta<TestListState>,
        filter: &TestFilterBuilder,
        workspace_root: Utf8PathBuf,
        env: EnvironmentMap,
        ecx: &EvalContext<'_>,
        bound: FilterBound,
        list_threads: usize,
    ) -> Result<Self, CreateTestListError>
    where
        I: IntoIterator<Item = RustTestArtifact<'g>>,
        I::IntoIter: Send,
    {
        let updated_dylib_path = Self::create_dylib_path(&rust_build_meta)?;
        debug!(
            "updated {}: {}",
            dylib_path_envvar(),
            updated_dylib_path.to_string_lossy(),
        );
        let lctx = LocalExecuteContext {
            rust_build_meta: &rust_build_meta,
            double_spawn: ctx.double_spawn,
            dylib_path: &updated_dylib_path,
            env: &env,
        };

        let runtime = Runtime::new().map_err(CreateTestListError::TokioRuntimeCreate)?;

        let stream = futures::stream::iter(test_artifacts).map(|test_binary| {
            async {
                let binary_match = filter.filter_binary_match(&test_binary, ecx, bound);
                match binary_match {
                    FilterBinaryMatch::Definite | FilterBinaryMatch::Possible => {
                        debug!(
                            "executing test binary to obtain test list \
                            (match result is {binary_match:?}): {}",
                            test_binary.binary_id,
                        );
                        // Run the binary to obtain the test list.
                        let (non_ignored, ignored) =
                            test_binary.exec(&lctx, ctx.target_runner).await?;
                        let (bin, info) = Self::process_output(
                            test_binary,
                            filter,
                            ecx,
                            bound,
                            non_ignored.as_str(),
                            ignored.as_str(),
                        )?;
                        Ok::<_, CreateTestListError>((bin, info))
                    }
                    FilterBinaryMatch::Mismatch { reason } => {
                        debug!("skipping test binary: {reason}: {}", test_binary.binary_id,);
                        Ok(Self::process_skipped(test_binary, reason))
                    }
                }
            }
        });
        let fut = stream.buffer_unordered(list_threads).try_collect();

        let rust_suites: BTreeMap<_, _> = runtime.block_on(fut)?;

        // Ensure that the runtime doesn't stay hanging even if a custom test framework misbehaves
        // (can be an issue on Windows).
        runtime.shutdown_background();

        let test_count = rust_suites
            .values()
            .map(|suite| suite.status.test_count())
            .sum();

        Ok(Self {
            rust_suites,
            workspace_root,
            env,
            rust_build_meta,
            updated_dylib_path,
            test_count,
            skip_counts: OnceLock::new(),
        })
    }

    /// Creates a new test list with the given binary names and outputs.
    #[cfg(test)]
    fn new_with_outputs(
        test_bin_outputs: impl IntoIterator<
            Item = (RustTestArtifact<'g>, impl AsRef<str>, impl AsRef<str>),
        >,
        workspace_root: Utf8PathBuf,
        rust_build_meta: RustBuildMeta<TestListState>,
        filter: &TestFilterBuilder,
        env: EnvironmentMap,
        ecx: &EvalContext<'_>,
        bound: FilterBound,
    ) -> Result<Self, CreateTestListError> {
        let mut test_count = 0;

        let updated_dylib_path = Self::create_dylib_path(&rust_build_meta)?;

        let rust_suites = test_bin_outputs
            .into_iter()
            .map(|(test_binary, non_ignored, ignored)| {
                let binary_match = filter.filter_binary_match(&test_binary, ecx, bound);
                match binary_match {
                    FilterBinaryMatch::Definite | FilterBinaryMatch::Possible => {
                        debug!(
                            "processing output for binary \
                            (match result is {binary_match:?}): {}",
                            test_binary.binary_id,
                        );
                        let (bin, info) = Self::process_output(
                            test_binary,
                            filter,
                            ecx,
                            bound,
                            non_ignored.as_ref(),
                            ignored.as_ref(),
                        )?;
                        test_count += info.status.test_count();
                        Ok((bin, info))
                    }
                    FilterBinaryMatch::Mismatch { reason } => {
                        debug!("skipping test binary: {reason}: {}", test_binary.binary_id,);
                        Ok(Self::process_skipped(test_binary, reason))
                    }
                }
            })
            .collect::<Result<BTreeMap<_, _>, _>>()?;

        Ok(Self {
            rust_suites,
            workspace_root,
            env,
            rust_build_meta,
            updated_dylib_path,
            test_count,
            skip_counts: OnceLock::new(),
        })
    }

    /// Returns the total number of tests across all binaries.
    pub fn test_count(&self) -> usize {
        self.test_count
    }

    /// Returns the Rust build-related metadata for this test list.
    pub fn rust_build_meta(&self) -> &RustBuildMeta<TestListState> {
        &self.rust_build_meta
    }

    /// Returns the total number of skipped tests.
    pub fn skip_counts(&self) -> &SkipCounts {
        self.skip_counts.get_or_init(|| {
            let mut skipped_tests_default_filter = 0;
            let skipped_tests = self
                .iter_tests()
                .filter(|instance| match instance.test_info.filter_match {
                    FilterMatch::Mismatch {
                        reason: MismatchReason::DefaultFilter,
                    } => {
                        skipped_tests_default_filter += 1;
                        true
                    }
                    FilterMatch::Mismatch { .. } => true,
                    FilterMatch::Matches => false,
                })
                .count();

            let mut skipped_binaries_default_filter = 0;
            let skipped_binaries = self
                .rust_suites
                .values()
                .filter(|suite| match suite.status {
                    RustTestSuiteStatus::Skipped {
                        reason: BinaryMismatchReason::DefaultSet,
                    } => {
                        skipped_binaries_default_filter += 1;
                        true
                    }
                    RustTestSuiteStatus::Skipped { .. } => true,
                    RustTestSuiteStatus::Listed { .. } => false,
                })
                .count();

            SkipCounts {
                skipped_tests,
                skipped_tests_default_filter,
                skipped_binaries,
                skipped_binaries_default_filter,
            }
        })
    }

    /// Returns the total number of tests that aren't skipped.
    ///
    /// It is always the case that `run_count + skip_count == test_count`.
    pub fn run_count(&self) -> usize {
        self.test_count - self.skip_counts().skipped_tests
    }

    /// Returns the total number of binaries that contain tests.
    pub fn binary_count(&self) -> usize {
        self.rust_suites.len()
    }

    /// Returns the total number of binaries that were listed (not skipped).
    pub fn listed_binary_count(&self) -> usize {
        self.binary_count() - self.skip_counts().skipped_binaries
    }

    /// Returns the mapped workspace root.
    pub fn workspace_root(&self) -> &Utf8Path {
        &self.workspace_root
    }

    /// Returns the environment variables to be used when running tests.
    pub fn cargo_env(&self) -> &EnvironmentMap {
        &self.env
    }

    /// Returns the updated dynamic library path used for tests.
    pub fn updated_dylib_path(&self) -> &OsStr {
        &self.updated_dylib_path
    }

    /// Constructs a serializble summary for this test list.
    pub fn to_summary(&self) -> TestListSummary {
        let rust_suites = self
            .rust_suites
            .values()
            .map(|test_suite| {
                let (status, test_cases) = test_suite.status.to_summary();
                let testsuite = RustTestSuiteSummary {
                    package_name: test_suite.package.name().to_owned(),
                    binary: RustTestBinarySummary {
                        binary_name: test_suite.binary_name.clone(),
                        package_id: test_suite.package.id().repr().to_owned(),
                        kind: test_suite.kind.clone(),
                        binary_path: test_suite.binary_path.clone(),
                        binary_id: test_suite.binary_id.clone(),
                        build_platform: test_suite.build_platform,
                    },
                    cwd: test_suite.cwd.clone(),
                    status,
                    test_cases,
                };
                (test_suite.binary_id.clone(), testsuite)
            })
            .collect();
        let mut summary = TestListSummary::new(self.rust_build_meta.to_summary());
        summary.test_count = self.test_count;
        summary.rust_suites = rust_suites;
        summary
    }

    /// Outputs this list to the given writer.
    pub fn write(
        &self,
        output_format: OutputFormat,
        writer: &mut dyn WriteStr,
        colorize: bool,
    ) -> Result<(), WriteTestListError> {
        match output_format {
            OutputFormat::Human { verbose } => self
                .write_human(writer, verbose, colorize)
                .map_err(WriteTestListError::Io),
            OutputFormat::Serializable(format) => format.to_writer(&self.to_summary(), writer),
        }
    }

    /// Iterates over all the test suites.
    pub fn iter(&self) -> impl Iterator<Item = &RustTestSuite> + '_ {
        self.rust_suites.values()
    }

    /// Iterates over the list of tests, returning the path and test name.
    pub fn iter_tests(&self) -> impl Iterator<Item = TestInstance<'_>> + '_ {
        self.rust_suites.values().flat_map(|test_suite| {
            test_suite
                .status
                .test_cases()
                .map(move |(name, test_info)| TestInstance::new(name, test_suite, test_info))
        })
    }

    /// Outputs this list as a string with the given format.
    pub fn to_string(&self, output_format: OutputFormat) -> Result<String, WriteTestListError> {
        let mut s = String::with_capacity(1024);
        self.write(output_format, &mut s, false)?;
        Ok(s)
    }

    // ---
    // Helper methods
    // ---

    // Empty list for tests.
    #[cfg(test)]
    pub(crate) fn empty() -> Self {
        Self {
            test_count: 0,
            workspace_root: Utf8PathBuf::new(),
            rust_build_meta: RustBuildMeta::empty(),
            env: EnvironmentMap::empty(),
            updated_dylib_path: OsString::new(),
            rust_suites: BTreeMap::new(),
            skip_counts: OnceLock::new(),
        }
    }

    pub(crate) fn create_dylib_path(
        rust_build_meta: &RustBuildMeta<TestListState>,
    ) -> Result<OsString, CreateTestListError> {
        let dylib_path = dylib_path();
        let dylib_path_is_empty = dylib_path.is_empty();
        let new_paths = rust_build_meta.dylib_paths();

        let mut updated_dylib_path: Vec<PathBuf> =
            Vec::with_capacity(dylib_path.len() + new_paths.len());
        updated_dylib_path.extend(
            new_paths
                .iter()
                .map(|path| path.clone().into_std_path_buf()),
        );
        updated_dylib_path.extend(dylib_path);

        // On macOS, these are the defaults when DYLD_FALLBACK_LIBRARY_PATH isn't set or set to an
        // empty string. (This is relevant if nextest is invoked as its own process and not
        // a Cargo subcommand.)
        //
        // This copies the logic from
        // https://cs.github.com/rust-lang/cargo/blob/7d289b171183578d45dcabc56db6db44b9accbff/src/cargo/core/compiler/compilation.rs#L292.
        if cfg!(target_os = "macos") && dylib_path_is_empty {
            if let Some(home) = home::home_dir() {
                updated_dylib_path.push(home.join("lib"));
            }
            updated_dylib_path.push("/usr/local/lib".into());
            updated_dylib_path.push("/usr/lib".into());
        }

        std::env::join_paths(updated_dylib_path)
            .map_err(move |error| CreateTestListError::dylib_join_paths(new_paths, error))
    }

    fn process_output(
        test_binary: RustTestArtifact<'g>,
        filter: &TestFilterBuilder,
        ecx: &EvalContext<'_>,
        bound: FilterBound,
        non_ignored: impl AsRef<str>,
        ignored: impl AsRef<str>,
    ) -> Result<(RustBinaryId, RustTestSuite<'g>), CreateTestListError> {
        let mut test_cases = BTreeMap::new();

        // Treat ignored and non-ignored as separate sets of single filters, so that partitioning
        // based on one doesn't affect the other.
        let mut non_ignored_filter = filter.build();
        for test_name in Self::parse(&test_binary.binary_id, non_ignored.as_ref())? {
            test_cases.insert(
                test_name.into(),
                RustTestCaseSummary {
                    ignored: false,
                    filter_match: non_ignored_filter.filter_match(
                        &test_binary,
                        test_name,
                        ecx,
                        bound,
                        false,
                    ),
                },
            );
        }

        let mut ignored_filter = filter.build();
        for test_name in Self::parse(&test_binary.binary_id, ignored.as_ref())? {
            // Note that libtest prints out:
            // * just ignored tests if --ignored is passed in
            // * all tests, both ignored and non-ignored, if --ignored is not passed in
            // Adding ignored tests after non-ignored ones makes everything resolve correctly.
            test_cases.insert(
                test_name.into(),
                RustTestCaseSummary {
                    ignored: true,
                    filter_match: ignored_filter.filter_match(
                        &test_binary,
                        test_name,
                        ecx,
                        bound,
                        true,
                    ),
                },
            );
        }

        Ok(test_binary.into_test_suite(RustTestSuiteStatus::Listed { test_cases }))
    }

    fn process_skipped(
        test_binary: RustTestArtifact<'g>,
        reason: BinaryMismatchReason,
    ) -> (RustBinaryId, RustTestSuite<'g>) {
        test_binary.into_test_suite(RustTestSuiteStatus::Skipped { reason })
    }

    /// Parses the output of --list --message-format terse and returns a sorted list.
    fn parse<'a>(
        binary_id: &'a RustBinaryId,
        list_output: &'a str,
    ) -> Result<Vec<&'a str>, CreateTestListError> {
        let mut list = Self::parse_impl(binary_id, list_output).collect::<Result<Vec<_>, _>>()?;
        list.sort_unstable();
        Ok(list)
    }

    fn parse_impl<'a>(
        binary_id: &'a RustBinaryId,
        list_output: &'a str,
    ) -> impl Iterator<Item = Result<&'a str, CreateTestListError>> + 'a {
        // The output is in the form:
        // <test name>: test
        // <test name>: test
        // ...

        list_output.lines().map(move |line| {
            line.strip_suffix(": test")
                .or_else(|| line.strip_suffix(": benchmark"))
                .ok_or_else(|| {
                    CreateTestListError::parse_line(
                        binary_id.clone(),
                        format!(
                            "line '{line}' did not end with the string ': test' or ': benchmark'"
                        ),
                        list_output,
                    )
                })
        })
    }

    /// Writes this test list out in a human-friendly format.
    pub fn write_human(
        &self,
        writer: &mut dyn WriteStr,
        verbose: bool,
        colorize: bool,
    ) -> io::Result<()> {
        self.write_human_impl(None, writer, verbose, colorize)
    }

    /// Writes this test list out in a human-friendly format with the given filter.
    pub(crate) fn write_human_with_filter(
        &self,
        filter: &TestListDisplayFilter<'_>,
        writer: &mut dyn WriteStr,
        verbose: bool,
        colorize: bool,
    ) -> io::Result<()> {
        self.write_human_impl(Some(filter), writer, verbose, colorize)
    }

    fn write_human_impl(
        &self,
        filter: Option<&TestListDisplayFilter<'_>>,
        mut writer: &mut dyn WriteStr,
        verbose: bool,
        colorize: bool,
    ) -> io::Result<()> {
        let mut styles = Styles::default();
        if colorize {
            styles.colorize();
        }

        for info in self.rust_suites.values() {
            let matcher = match filter {
                Some(filter) => match filter.matcher_for(&info.binary_id) {
                    Some(matcher) => matcher,
                    None => continue,
                },
                None => DisplayFilterMatcher::All,
            };

            // Skip this binary if there are no tests within it that will be run, and this isn't
            // verbose output.
            if !verbose
                && info
                    .status
                    .test_cases()
                    .all(|(_, test_case)| !test_case.filter_match.is_match())
            {
                continue;
            }

            writeln!(writer, "{}:", info.binary_id.style(styles.binary_id))?;
            if verbose {
                writeln!(
                    writer,
                    "  {} {}",
                    "bin:".style(styles.field),
                    info.binary_path
                )?;
                writeln!(writer, "  {} {}", "cwd:".style(styles.field), info.cwd)?;
                writeln!(
                    writer,
                    "  {} {}",
                    "build platform:".style(styles.field),
                    info.build_platform,
                )?;
            }

            let mut indented = indented(writer).with_str("    ");

            match &info.status {
                RustTestSuiteStatus::Listed { test_cases } => {
                    let matching_tests: Vec<_> = test_cases
                        .iter()
                        .filter(|(name, _)| matcher.is_match(name))
                        .collect();
                    if matching_tests.is_empty() {
                        writeln!(indented, "(no tests)")?;
                    } else {
                        for (name, info) in matching_tests {
                            match (verbose, info.filter_match.is_match()) {
                                (_, true) => {
                                    write_test_name(name, &styles, &mut indented)?;
                                    writeln!(indented)?;
                                }
                                (true, false) => {
                                    write_test_name(name, &styles, &mut indented)?;
                                    writeln!(indented, " (skipped)")?;
                                }
                                (false, false) => {
                                    // Skip printing this test entirely if it isn't a match.
                                }
                            }
                        }
                    }
                }
                RustTestSuiteStatus::Skipped { reason } => {
                    writeln!(indented, "(test binary {reason}, skipped)")?;
                }
            }

            writer = indented.into_inner();
        }
        Ok(())
    }
}

/// A suite of tests within a single Rust test binary.
///
/// This is a representation of [`nextest_metadata::RustTestSuiteSummary`] used internally by the runner.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct RustTestSuite<'g> {
    /// A unique identifier for this binary.
    pub binary_id: RustBinaryId,

    /// The path to the binary.
    pub binary_path: Utf8PathBuf,

    /// Package metadata.
    pub package: PackageMetadata<'g>,

    /// The unique binary name defined in `Cargo.toml` or inferred by the filename.
    pub binary_name: String,

    /// The kind of Rust test binary this is.
    pub kind: RustTestBinaryKind,

    /// The working directory that this test binary will be executed in. If None, the current directory
    /// will not be changed.
    pub cwd: Utf8PathBuf,

    /// The platform the test suite is for (host or target).
    pub build_platform: BuildPlatform,

    /// Non-test binaries corresponding to this test suite (name, path).
    pub non_test_binaries: BTreeSet<(String, Utf8PathBuf)>,

    /// Test suite status and test case names.
    pub status: RustTestSuiteStatus,
}

impl<'g> RustTestArtifact<'g> {
    /// Run this binary with and without --ignored and get the corresponding outputs.
    async fn exec(
        &self,
        lctx: &LocalExecuteContext<'_>,
        target_runner: &TargetRunner,
    ) -> Result<(String, String), CreateTestListError> {
        // This error situation has been known to happen with reused builds. It produces
        // a really terrible and confusing "file not found" message if allowed to prceed.
        if !self.cwd.is_dir() {
            return Err(CreateTestListError::CwdIsNotDir {
                binary_id: self.binary_id.clone(),
                cwd: self.cwd.clone(),
            });
        }
        let platform_runner = target_runner.for_build_platform(self.build_platform);

        let non_ignored = self.exec_single(false, lctx, platform_runner);
        let ignored = self.exec_single(true, lctx, platform_runner);

        let (non_ignored_out, ignored_out) = futures::future::join(non_ignored, ignored).await;
        Ok((non_ignored_out?, ignored_out?))
    }

    async fn exec_single(
        &self,
        ignored: bool,
        lctx: &LocalExecuteContext<'_>,
        runner: Option<&PlatformRunner>,
    ) -> Result<String, CreateTestListError> {
        let mut argv = Vec::new();

        let program: String = if let Some(runner) = runner {
            argv.extend(runner.args());
            argv.push(self.binary_path.as_str());
            runner.binary().into()
        } else {
            debug_assert!(
                self.binary_path.is_absolute(),
                "binary path {} is absolute",
                self.binary_path
            );
            self.binary_path.clone().into()
        };

        argv.extend(["--list", "--format", "terse"]);
        if ignored {
            argv.push("--ignored");
        }

        let cmd = TestCommand::new(
            lctx,
            program.clone(),
            &argv,
            &self.cwd,
            &self.package,
            &self.non_test_binaries,
        );

        let output =
            cmd.wait_with_output()
                .await
                .map_err(|error| CreateTestListError::CommandExecFail {
                    binary_id: self.binary_id.clone(),
                    command: std::iter::once(program.clone())
                        .chain(argv.iter().map(|&s| s.to_owned()))
                        .collect(),
                    error,
                })?;

        if output.status.success() {
            String::from_utf8(output.stdout).map_err(|err| CreateTestListError::CommandNonUtf8 {
                binary_id: self.binary_id.clone(),
                command: std::iter::once(program)
                    .chain(argv.iter().map(|&s| s.to_owned()))
                    .collect(),
                stdout: err.into_bytes(),
                stderr: output.stderr,
            })
        } else {
            Err(CreateTestListError::CommandFail {
                binary_id: self.binary_id.clone(),
                command: std::iter::once(program)
                    .chain(argv.iter().map(|&s| s.to_owned()))
                    .collect(),
                exit_status: output.status,
                stdout: output.stdout,
                stderr: output.stderr,
            })
        }
    }
}

/// Serializable information about the status of and test cases within a test suite.
///
/// Part of a [`RustTestSuiteSummary`].
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum RustTestSuiteStatus {
    /// The test suite was executed with `--list` and the list of test cases was obtained.
    Listed {
        /// The test cases contained within this test suite.
        test_cases: BTreeMap<String, RustTestCaseSummary>,
    },

    /// The test suite was not executed.
    Skipped {
        /// The reason why the test suite was skipped.
        reason: BinaryMismatchReason,
    },
}

static EMPTY_TEST_CASE_MAP: BTreeMap<String, RustTestCaseSummary> = BTreeMap::new();

impl RustTestSuiteStatus {
    /// Returns the number of test cases within this suite.
    pub fn test_count(&self) -> usize {
        match self {
            RustTestSuiteStatus::Listed { test_cases } => test_cases.len(),
            RustTestSuiteStatus::Skipped { .. } => 0,
        }
    }

    /// Returns the list of test cases within this suite.
    pub fn test_cases(&self) -> impl Iterator<Item = (&str, &RustTestCaseSummary)> + '_ {
        match self {
            RustTestSuiteStatus::Listed { test_cases } => test_cases.iter(),
            RustTestSuiteStatus::Skipped { .. } => {
                // Return an empty test case.
                EMPTY_TEST_CASE_MAP.iter()
            }
        }
        .map(|(name, case)| (name.as_str(), case))
    }

    /// Converts this status to its serializable form.
    pub fn to_summary(
        &self,
    ) -> (
        RustTestSuiteStatusSummary,
        BTreeMap<String, RustTestCaseSummary>,
    ) {
        match self {
            Self::Listed { test_cases } => (RustTestSuiteStatusSummary::LISTED, test_cases.clone()),
            Self::Skipped {
                reason: BinaryMismatchReason::Expression,
            } => (RustTestSuiteStatusSummary::SKIPPED, BTreeMap::new()),
            Self::Skipped {
                reason: BinaryMismatchReason::DefaultSet,
            } => (
                RustTestSuiteStatusSummary::SKIPPED_DEFAULT_FILTER,
                BTreeMap::new(),
            ),
        }
    }
}

/// Represents a single test with its associated binary.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct TestInstance<'a> {
    /// The name of the test.
    pub name: &'a str,

    /// Information about the test suite.
    pub suite_info: &'a RustTestSuite<'a>,

    /// Information about the test.
    pub test_info: &'a RustTestCaseSummary,
}

impl<'a> TestInstance<'a> {
    /// Creates a new `TestInstance`.
    pub(crate) fn new(
        name: &'a (impl AsRef<str> + ?Sized),
        suite_info: &'a RustTestSuite,
        test_info: &'a RustTestCaseSummary,
    ) -> Self {
        Self {
            name: name.as_ref(),
            suite_info,
            test_info,
        }
    }

    /// Return a reasonable key for sorting. This is (binary ID, test name).
    #[inline]
    pub(crate) fn sort_key(&self) -> (&'a str, &'a str) {
        ((self.suite_info.binary_id.as_str()), self.name)
    }

    /// Returns the corresponding [`TestQuery`] for this `TestInstance`.
    pub fn to_test_query(&self) -> TestQuery<'a> {
        TestQuery {
            binary_query: BinaryQuery {
                package_id: self.suite_info.package.id(),
                binary_id: &self.suite_info.binary_id,
                kind: &self.suite_info.kind,
                binary_name: &self.suite_info.binary_name,
                platform: convert_build_platform(self.suite_info.build_platform),
            },
            test_name: self.name,
        }
    }

    /// Creates the command for this test instance.
    pub(crate) fn make_command(
        &self,
        ctx: &TestExecuteContext<'_>,
        test_list: &TestList<'_>,
    ) -> TestCommand {
        let platform_runner = ctx
            .target_runner
            .for_build_platform(self.suite_info.build_platform);
        // TODO: non-rust tests

        let mut args = Vec::new();

        let program: String = match platform_runner {
            Some(runner) => {
                args.extend(runner.args());
                args.push(self.suite_info.binary_path.as_str());
                runner.binary().into()
            }
            None => self.suite_info.binary_path.to_owned().into(),
        };

        args.extend(["--exact", self.name, "--nocapture"]);
        if self.test_info.ignored {
            args.push("--ignored");
        }

        let lctx = LocalExecuteContext {
            rust_build_meta: &test_list.rust_build_meta,
            double_spawn: ctx.double_spawn,
            dylib_path: test_list.updated_dylib_path(),
            env: &test_list.env,
        };

        TestCommand::new(
            &lctx,
            program,
            &args,
            &self.suite_info.cwd,
            &self.suite_info.package,
            &self.suite_info.non_test_binaries,
        )
    }
}

/// Context required for test execution.
#[derive(Clone, Debug)]
pub struct TestExecuteContext<'a> {
    /// Double-spawn info.
    pub double_spawn: &'a DoubleSpawnInfo,

    /// Target runner.
    pub target_runner: &'a TargetRunner,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        cargo_config::{TargetDefinitionLocation, TargetTriple, TargetTripleSource},
        list::SerializableFormat,
        platform::{BuildPlatforms, HostPlatform, PlatformLibdir, TargetPlatform},
        test_filter::{RunIgnored, TestFilterPatterns},
    };
    use guppy::CargoMetadata;
    use indoc::indoc;
    use maplit::btreemap;
    use nextest_filtering::{CompiledExpr, Filterset, FiltersetKind, ParseContext};
    use nextest_metadata::{FilterMatch, MismatchReason, PlatformLibdirUnavailable};
    use once_cell::sync::Lazy;
    use pretty_assertions::assert_eq;
    use target_spec::Platform;

    #[test]
    fn test_parse_test_list() {
        // Lines ending in ': benchmark' (output by the default Rust bencher) should be skipped.
        let non_ignored_output = indoc! {"
            tests::foo::test_bar: test
            tests::baz::test_quux: test
            benches::bench_foo: benchmark
        "};
        let ignored_output = indoc! {"
            tests::ignored::test_bar: test
            tests::baz::test_ignored: test
            benches::ignored_bench_foo: benchmark
        "};

        let cx = ParseContext {
            graph: &PACKAGE_GRAPH_FIXTURE,
            kind: FiltersetKind::Test,
        };

        let test_filter = TestFilterBuilder::new(
            RunIgnored::Default,
            None,
            TestFilterPatterns::default(),
            // Test against the platform() predicate because this is the most important one here.
            vec![Filterset::parse("platform(target)".to_owned(), &cx).unwrap()],
        )
        .unwrap();
        let fake_cwd: Utf8PathBuf = "/fake/cwd".into();
        let fake_binary_name = "fake-binary".to_owned();
        let fake_binary_id = RustBinaryId::new("fake-package::fake-binary");

        let test_binary = RustTestArtifact {
            binary_path: "/fake/binary".into(),
            cwd: fake_cwd.clone(),
            package: package_metadata(),
            binary_name: fake_binary_name.clone(),
            binary_id: fake_binary_id.clone(),
            kind: RustTestBinaryKind::LIB,
            non_test_binaries: BTreeSet::new(),
            build_platform: BuildPlatform::Target,
        };

        let skipped_binary_name = "skipped-binary".to_owned();
        let skipped_binary_id = RustBinaryId::new("fake-package::skipped-binary");
        let skipped_binary = RustTestArtifact {
            binary_path: "/fake/skipped-binary".into(),
            cwd: fake_cwd.clone(),
            package: package_metadata(),
            binary_name: skipped_binary_name.clone(),
            binary_id: skipped_binary_id.clone(),
            kind: RustTestBinaryKind::PROC_MACRO,
            non_test_binaries: BTreeSet::new(),
            build_platform: BuildPlatform::Host,
        };

        let fake_triple = TargetTriple {
            platform: Platform::new(
                "aarch64-unknown-linux-gnu",
                target_spec::TargetFeatures::Unknown,
            )
            .unwrap(),
            source: TargetTripleSource::CliOption,
            location: TargetDefinitionLocation::Builtin,
        };
        let fake_host_libdir = "/home/fake/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib";
        let build_platforms = BuildPlatforms {
            host: HostPlatform {
                platform: TargetTriple::x86_64_unknown_linux_gnu().platform,
                libdir: PlatformLibdir::Available(fake_host_libdir.into()),
            },
            target: Some(TargetPlatform {
                triple: fake_triple,
                // Test an unavailable libdir.
                libdir: PlatformLibdir::Unavailable(PlatformLibdirUnavailable::new_const("test")),
            }),
        };

        let fake_env = EnvironmentMap::empty();
        let rust_build_meta =
            RustBuildMeta::new("/fake", build_platforms).map_paths(&PathMapper::noop());
        let ecx = EvalContext {
            default_filter: &CompiledExpr::ALL,
        };
        let test_list = TestList::new_with_outputs(
            [
                (test_binary, &non_ignored_output, &ignored_output),
                (
                    skipped_binary,
                    &"should-not-show-up-stdout",
                    &"should-not-show-up-stderr",
                ),
            ],
            Utf8PathBuf::from("/fake/path"),
            rust_build_meta,
            &test_filter,
            fake_env,
            &ecx,
            FilterBound::All,
        )
        .expect("valid output");
        assert_eq!(
            test_list.rust_suites,
            btreemap! {
                fake_binary_id.clone() => RustTestSuite {
                    status: RustTestSuiteStatus::Listed {
                        test_cases: btreemap! {
                            "tests::foo::test_bar".to_owned() => RustTestCaseSummary {
                                ignored: false,
                                filter_match: FilterMatch::Matches,
                            },
                            "tests::baz::test_quux".to_owned() => RustTestCaseSummary {
                                ignored: false,
                                filter_match: FilterMatch::Matches,
                            },
                            "benches::bench_foo".to_owned() => RustTestCaseSummary {
                                ignored: false,
                                filter_match: FilterMatch::Matches,
                            },
                            "tests::ignored::test_bar".to_owned() => RustTestCaseSummary {
                                ignored: true,
                                filter_match: FilterMatch::Mismatch { reason: MismatchReason::Ignored },
                            },
                            "tests::baz::test_ignored".to_owned() => RustTestCaseSummary {
                                ignored: true,
                                filter_match: FilterMatch::Mismatch { reason: MismatchReason::Ignored },
                            },
                            "benches::ignored_bench_foo".to_owned() => RustTestCaseSummary {
                                ignored: true,
                                filter_match: FilterMatch::Mismatch { reason: MismatchReason::Ignored },
                            },
                        },
                    },
                    cwd: fake_cwd.clone(),
                    build_platform: BuildPlatform::Target,
                    package: package_metadata(),
                    binary_name: fake_binary_name,
                    binary_id: fake_binary_id,
                    binary_path: "/fake/binary".into(),
                    kind: RustTestBinaryKind::LIB,
                    non_test_binaries: BTreeSet::new(),
                },
                skipped_binary_id.clone() => RustTestSuite {
                    status: RustTestSuiteStatus::Skipped {
                        reason: BinaryMismatchReason::Expression,
                    },
                    cwd: fake_cwd,
                    build_platform: BuildPlatform::Host,
                    package: package_metadata(),
                    binary_name: skipped_binary_name,
                    binary_id: skipped_binary_id,
                    binary_path: "/fake/skipped-binary".into(),
                    kind: RustTestBinaryKind::PROC_MACRO,
                    non_test_binaries: BTreeSet::new(),
                },
            }
        );

        // Check that the expected outputs are valid.
        static EXPECTED_HUMAN: &str = indoc! {"
        fake-package::fake-binary:
            benches::bench_foo
            tests::baz::test_quux
            tests::foo::test_bar
        "};
        static EXPECTED_HUMAN_VERBOSE: &str = indoc! {"
            fake-package::fake-binary:
              bin: /fake/binary
              cwd: /fake/cwd
              build platform: target
                benches::bench_foo
                benches::ignored_bench_foo (skipped)
                tests::baz::test_ignored (skipped)
                tests::baz::test_quux
                tests::foo::test_bar
                tests::ignored::test_bar (skipped)
            fake-package::skipped-binary:
              bin: /fake/skipped-binary
              cwd: /fake/cwd
              build platform: host
                (test binary didn't match filtersets, skipped)
        "};
        static EXPECTED_JSON_PRETTY: &str = indoc! {r#"
            {
              "rust-build-meta": {
                "target-directory": "/fake",
                "base-output-directories": [],
                "non-test-binaries": {},
                "build-script-out-dirs": {},
                "linked-paths": [],
                "platforms": {
                  "host": {
                    "platform": {
                      "triple": "x86_64-unknown-linux-gnu",
                      "target-features": "unknown"
                    },
                    "libdir": {
                      "status": "available",
                      "path": "/home/fake/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib"
                    }
                  },
                  "targets": [
                    {
                      "platform": {
                        "triple": "aarch64-unknown-linux-gnu",
                        "target-features": "unknown"
                      },
                      "libdir": {
                        "status": "unavailable",
                        "reason": "test"
                      }
                    }
                  ]
                },
                "target-platforms": [
                  {
                    "triple": "aarch64-unknown-linux-gnu",
                    "target-features": "unknown"
                  }
                ],
                "target-platform": "aarch64-unknown-linux-gnu"
              },
              "test-count": 6,
              "rust-suites": {
                "fake-package::fake-binary": {
                  "package-name": "metadata-helper",
                  "binary-id": "fake-package::fake-binary",
                  "binary-name": "fake-binary",
                  "package-id": "metadata-helper 0.1.0 (path+file:///Users/fakeuser/local/testcrates/metadata/metadata-helper)",
                  "kind": "lib",
                  "binary-path": "/fake/binary",
                  "build-platform": "target",
                  "cwd": "/fake/cwd",
                  "status": "listed",
                  "testcases": {
                    "benches::bench_foo": {
                      "ignored": false,
                      "filter-match": {
                        "status": "matches"
                      }
                    },
                    "benches::ignored_bench_foo": {
                      "ignored": true,
                      "filter-match": {
                        "status": "mismatch",
                        "reason": "ignored"
                      }
                    },
                    "tests::baz::test_ignored": {
                      "ignored": true,
                      "filter-match": {
                        "status": "mismatch",
                        "reason": "ignored"
                      }
                    },
                    "tests::baz::test_quux": {
                      "ignored": false,
                      "filter-match": {
                        "status": "matches"
                      }
                    },
                    "tests::foo::test_bar": {
                      "ignored": false,
                      "filter-match": {
                        "status": "matches"
                      }
                    },
                    "tests::ignored::test_bar": {
                      "ignored": true,
                      "filter-match": {
                        "status": "mismatch",
                        "reason": "ignored"
                      }
                    }
                  }
                },
                "fake-package::skipped-binary": {
                  "package-name": "metadata-helper",
                  "binary-id": "fake-package::skipped-binary",
                  "binary-name": "skipped-binary",
                  "package-id": "metadata-helper 0.1.0 (path+file:///Users/fakeuser/local/testcrates/metadata/metadata-helper)",
                  "kind": "proc-macro",
                  "binary-path": "/fake/skipped-binary",
                  "build-platform": "host",
                  "cwd": "/fake/cwd",
                  "status": "skipped",
                  "testcases": {}
                }
              }
            }"#};

        assert_eq!(
            test_list
                .to_string(OutputFormat::Human { verbose: false })
                .expect("human succeeded"),
            EXPECTED_HUMAN
        );
        assert_eq!(
            test_list
                .to_string(OutputFormat::Human { verbose: true })
                .expect("human succeeded"),
            EXPECTED_HUMAN_VERBOSE
        );
        println!(
            "{}",
            test_list
                .to_string(OutputFormat::Serializable(SerializableFormat::JsonPretty))
                .expect("json-pretty succeeded")
        );
        assert_eq!(
            test_list
                .to_string(OutputFormat::Serializable(SerializableFormat::JsonPretty))
                .expect("json-pretty succeeded"),
            EXPECTED_JSON_PRETTY
        );
    }

    static PACKAGE_GRAPH_FIXTURE: Lazy<PackageGraph> = Lazy::new(|| {
        static FIXTURE_JSON: &str = include_str!("../../../fixtures/cargo-metadata.json");
        let metadata = CargoMetadata::parse_json(FIXTURE_JSON).expect("fixture is valid JSON");
        metadata
            .build_graph()
            .expect("fixture is valid PackageGraph")
    });

    static PACKAGE_METADATA_ID: &str = "metadata-helper 0.1.0 (path+file:///Users/fakeuser/local/testcrates/metadata/metadata-helper)";
    fn package_metadata() -> PackageMetadata<'static> {
        PACKAGE_GRAPH_FIXTURE
            .metadata(&PackageId::new(PACKAGE_METADATA_ID))
            .expect("package ID is valid")
    }
}