ruff/crates/ty_server/tests/e2e/pull_diagnostics.rs

use anyhow::Result;
use insta::assert_debug_snapshot;
use lsp_types::request::WorkspaceDiagnosticRequest;
use lsp_types::{
    PartialResultParams, PreviousResultId, Url, WorkDoneProgressParams, WorkspaceDiagnosticParams,
    WorkspaceDiagnosticReportResult, WorkspaceDocumentDiagnosticReport,
};
use ruff_db::system::SystemPath;
use ty_server::{ClientOptions, DiagnosticMode, PartialWorkspaceProgress};

use crate::{TestServer, TestServerBuilder, TestServerError};

#[test]
fn on_did_open() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let foo = SystemPath::new("src/foo.py");
    let foo_content = "\
def foo() -> str:
    return 42
";

    let mut server = TestServerBuilder::new()?
        .with_workspace(workspace_root, ClientOptions::default())?
        .with_file(foo, foo_content)?
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()?;

    server.open_text_document(foo, &foo_content, 1);
    let diagnostics = server.document_diagnostic_request(foo, None)?;

    assert_debug_snapshot!(diagnostics);

    Ok(())
}

#[test]
fn document_diagnostic_caching_unchanged() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let foo = SystemPath::new("src/foo.py");
    let foo_content = "\
def foo() -> str:
    return 42
";

    let mut server = TestServerBuilder::new()?
        .with_workspace(workspace_root, ClientOptions::default())?
        .with_file(foo, foo_content)?
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()?;

    server.open_text_document(foo, &foo_content, 1);

    // First request with no previous result ID
    let first_response = server.document_diagnostic_request(foo, None)?;

    // Extract result ID from first response
    let result_id = match &first_response {
        lsp_types::DocumentDiagnosticReportResult::Report(
            lsp_types::DocumentDiagnosticReport::Full(report),
        ) => report
            .full_document_diagnostic_report
            .result_id
            .as_ref()
            .expect("First response should have a result ID")
            .clone(),
        _ => panic!("First response should be a full report"),
    };

    // Second request with the previous result ID - should return Unchanged
    let second_response = server.document_diagnostic_request(foo, Some(result_id))?;

    // Verify it's an unchanged report
    match second_response {
        lsp_types::DocumentDiagnosticReportResult::Report(
            lsp_types::DocumentDiagnosticReport::Unchanged(_),
        ) => {
            // Success - got unchanged report as expected
        }
        _ => panic!("Expected an unchanged report when diagnostics haven't changed"),
    }

    Ok(())
}

#[test]
fn document_diagnostic_caching_changed() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let foo = SystemPath::new("src/foo.py");
    let foo_content_v1 = "\
def foo() -> str:
    return 42
";
    let foo_content_v2 = "\
def foo() -> str:
    return \"fixed\"
";

    let mut server = TestServerBuilder::new()?
        .with_workspace(workspace_root, ClientOptions::default())?
        .with_file(foo, foo_content_v1)?
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()?;

    server.open_text_document(foo, &foo_content_v1, 1);

    // First request with no previous result ID
    let first_response = server.document_diagnostic_request(foo, None)?;

    // Extract result ID from first response
    let result_id = match &first_response {
        lsp_types::DocumentDiagnosticReportResult::Report(
            lsp_types::DocumentDiagnosticReport::Full(report),
        ) => report
            .full_document_diagnostic_report
            .result_id
            .as_ref()
            .expect("First response should have a result ID")
            .clone(),
        _ => panic!("First response should be a full report"),
    };

    // Change the document to fix the error
    server.change_text_document(
        foo,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: foo_content_v2.to_string(),
        }],
        2,
    );

    // Second request with the previous result ID - should return a new full report
    let second_response = server.document_diagnostic_request(foo, Some(result_id))?;

    // Verify it's a full report (not unchanged)
    match second_response {
        lsp_types::DocumentDiagnosticReportResult::Report(
            lsp_types::DocumentDiagnosticReport::Full(report),
        ) => {
            // Should have no diagnostics now
            assert_eq!(report.full_document_diagnostic_report.items.len(), 0);
        }
        _ => panic!("Expected a full report when diagnostics have changed"),
    }

    Ok(())
}

#[test]
fn workspace_diagnostic_caching() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");

    // File A: Will have an unchanged diagnostic
    let file_a = SystemPath::new("src/unchanged.py");
    let file_a_content = "\
def foo() -> str:
    return 42  # This error will remain the same
";

    // File B: Initially no error, will get a new error (added diagnostic)
    let file_b = SystemPath::new("src/new_error.py");
    let file_b_content_v1 = "\
def foo() -> int:
    return 42  # No error initially
";
    let file_b_content_v2 = "\
def foo() -> str:
    return 42  # Error appears
";

    // File C: Initially has error, will be fixed (removed diagnostic)
    let file_c = SystemPath::new("src/fixed_error.py");
    let file_c_content_v1 = "\
def foo() -> str:
    return 42  # Error initially
";
    let file_c_content_v2 = "\
def foo() -> str:
    return \"fixed\"  # Error removed
";

    // File D: Has error that changes content (changed diagnostic)
    let file_d = SystemPath::new("src/changed_error.py");
    let file_d_content_v1 = "\
def foo() -> str:
    return 42  # First error: expected str, got int
";
    let file_d_content_v2 = "\
def foo() -> int:
    return \"hello\"  # Different error: expected int, got str
";

    // File E: Modified but same diagnostic (e.g., new function added but original error remains)
    let file_e = SystemPath::new("src/modified_same_error.py");
    let file_e_content_v1 = "\
def foo() -> str:
    return 42  # Error: expected str, got int
";
    let file_e_content_v2 = "\
def bar() -> int:
    return 100  # New function added at the top

def foo() -> str:
    return 42  # Same error: expected str, got int
";

    let global_options = ClientOptions::default().with_diagnostic_mode(DiagnosticMode::Workspace);

    let mut server = TestServerBuilder::new()?
        .with_workspace(
            workspace_root,
            ClientOptions::default().with_diagnostic_mode(DiagnosticMode::Workspace),
        )?
        .with_initialization_options(global_options)
        .with_file(file_a, file_a_content)?
        .with_file(file_b, file_b_content_v1)?
        .with_file(file_c, file_c_content_v1)?
        .with_file(file_d, file_d_content_v1)?
        .with_file(file_e, file_e_content_v1)?
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()?;

    server.open_text_document(file_a, &file_a_content, 1);

    // First request with no previous result IDs
    let mut first_response = server.workspace_diagnostic_request(None)?;
    sort_workspace_diagnostic_response(&mut first_response);

    assert_debug_snapshot!("workspace_diagnostic_initial_state", first_response);

    // Consume all progress notifications sent during workspace diagnostics
    consume_all_progress_notifications(&mut server)?;

    // Extract result IDs from the first response
    let previous_result_ids = extract_result_ids_from_response(&first_response);

    // Make changes to files B, C, D, and E (leave A unchanged)
    // Need to open files before changing them
    server.open_text_document(file_b, &file_b_content_v1, 1);
    server.open_text_document(file_c, &file_c_content_v1, 1);
    server.open_text_document(file_d, &file_d_content_v1, 1);
    server.open_text_document(file_e, &file_e_content_v1, 1);

    // File B: Add a new error
    server.change_text_document(
        file_b,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_b_content_v2.to_string(),
        }],
        2,
    );

    // File C: Fix the error
    server.change_text_document(
        file_c,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_c_content_v2.to_string(),
        }],
        2,
    );

    // File D: Change the error
    server.change_text_document(
        file_d,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_d_content_v2.to_string(),
        }],
        2,
    );

    // File E: Modify the file but keep the same diagnostic
    server.change_text_document(
        file_e,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_e_content_v2.to_string(),
        }],
        2,
    );

    // Second request with previous result IDs
    // Expected results:
    // - File A: Unchanged report (diagnostic hasn't changed)
    // - File B: Full report (new diagnostic appeared)
    // - File C: Full report with empty diagnostics (diagnostic was removed)
    // - File D: Full report (diagnostic content changed)
    // - File E: Full report (the range changes)
    let mut second_response = server.workspace_diagnostic_request(Some(previous_result_ids))?;
    sort_workspace_diagnostic_response(&mut second_response);

    // Consume all progress notifications sent during the second workspace diagnostics
    consume_all_progress_notifications(&mut server)?;

    assert_debug_snapshot!("workspace_diagnostic_after_changes", second_response);

    Ok(())
}

// Redact result_id values since they are hash-based and non-deterministic
fn filter_result_id() -> insta::internals::SettingsBindDropGuard {
    let mut settings = insta::Settings::clone_current();
    settings.add_filter(r#""[a-f0-9]{16}""#, r#""[RESULT_ID]""#);
    settings.bind_to_scope()
}

fn consume_all_progress_notifications(server: &mut TestServer) -> Result<()> {
    // Always consume Begin
    let begin_params = server.await_notification::<lsp_types::notification::Progress>()?;

    // The params are already the ProgressParams type
    let lsp_types::ProgressParamsValue::WorkDone(lsp_types::WorkDoneProgress::Begin(_)) =
        begin_params.value
    else {
        return Err(anyhow::anyhow!("Expected Begin progress notification"));
    };

    // Consume Report notifications - there may be multiple based on number of files
    // Keep consuming until we hit the End notification
    loop {
        let params = server.await_notification::<lsp_types::notification::Progress>()?;

        if let lsp_types::ProgressParamsValue::WorkDone(lsp_types::WorkDoneProgress::End(_)) =
            params.value
        {
            // Found the End notification, we're done
            break;
        }
        // Otherwise it's a Report notification, continue
    }

    Ok(())
}

/// Tests that the server sends partial results for workspace diagnostics
/// if a client sets the `partial_result_token` in the request.
///
/// Note: In production, the server throttles the partial results to one every 50ms. However,
/// this behavior makes testing very hard. That's why the server, in tests, sends a partial response
/// as soon as it batched at least 2 diagnostics together.
#[test]
fn workspace_diagnostic_streaming() -> Result<()> {
    const NUM_FILES: usize = 5;

    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");

    // Create 60 files with the same error to trigger streaming batching (server batches at 50 files)
    let error_content = "\
def foo() -> str:
    return 42  # Type error: expected str, got int
";

    let global_options = ClientOptions::default().with_diagnostic_mode(DiagnosticMode::Workspace);

    let mut builder = TestServerBuilder::new()?
        .with_workspace(
            workspace_root,
            ClientOptions::default().with_diagnostic_mode(DiagnosticMode::Workspace),
        )?
        .with_initialization_options(global_options);

    for i in 0..NUM_FILES {
        let file_path_string = format!("src/file_{i:03}.py");
        let file_path = SystemPath::new(&file_path_string);
        builder = builder.with_file(file_path, error_content)?;
    }

    let mut server = builder
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()?;

    let partial_token = lsp_types::ProgressToken::String("streaming-diagnostics".to_string());
    let request_id = server.send_request::<WorkspaceDiagnosticRequest>(WorkspaceDiagnosticParams {
        identifier: None,
        previous_result_ids: Vec::new(),
        work_done_progress_params: WorkDoneProgressParams {
            work_done_token: None,
        },
        partial_result_params: PartialResultParams {
            partial_result_token: Some(partial_token.clone()),
        },
    });

    let mut received_results = 0usize;

    // First, read the response of the workspace diagnostic request.
    // Note: This response comes after the progress notifications but it simplifies the test to read it first.
    let final_response = server.await_response::<WorkspaceDiagnosticReportResult>(&request_id)?;

    // Process the final report.
    // This should always be a partial report. However, the type definition in the LSP specification
    // is broken in the sense that both `Report` and `Partial` have the exact same shape
    // and deserializing a previously serialized `Partial` result will yield a `Report` type.
    let response_items = match final_response {
        WorkspaceDiagnosticReportResult::Report(report) => report.items,
        WorkspaceDiagnosticReportResult::Partial(partial) => partial.items,
    };

    // The last batch should contain 1 item because the server sends a partial result with
    // 2 items each.
    assert_eq!(response_items.len(), 1);
    received_results += response_items.len();

    // Collect any partial results sent via progress notifications
    while let Ok(params) = server.await_notification::<PartialWorkspaceProgress>() {
        if params.token == partial_token {
            let streamed_items = match params.value {
                // Ideally we'd assert that only the first response is a full report
                // However, the type definition in the LSP specification is broken
                // in the sense that both `Report` and `Partial` have the exact same structure
                // but it also doesn't use a tag to tell them apart...
                // That means, a client can never tell if it's a full report or a partial report
                WorkspaceDiagnosticReportResult::Report(report) => report.items,
                WorkspaceDiagnosticReportResult::Partial(partial) => partial.items,
            };

            // All streamed batches should contain 2 items (test behavior).
            assert_eq!(streamed_items.len(), 2);
            received_results += streamed_items.len();

            if received_results == NUM_FILES {
                break;
            }
        }
    }

    assert_eq!(received_results, NUM_FILES);

    Ok(())
}

/// Tests that the server's diagnostic streaming (partial results) work correctly
/// with result ids.
#[test]
fn workspace_diagnostic_streaming_with_caching() -> Result<()> {
    const NUM_FILES: usize = 7;

    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let error_content = "def foo() -> str:\n    return 42  # Error";
    let changed_content = "def foo() -> str:\n    return true  # Error";

    let global_options = ClientOptions::default().with_diagnostic_mode(DiagnosticMode::Workspace);

    let mut builder = TestServerBuilder::new()?
        .with_workspace(workspace_root, global_options.clone())?
        .with_initialization_options(global_options);

    for i in 0..NUM_FILES {
        let file_path_string = format!("src/error_{i}.py");
        let file_path = SystemPath::new(&file_path_string);
        builder = builder.with_file(file_path, error_content)?; // All files have errors initially
    }

    let mut server = builder
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()?;

    server.open_text_document(SystemPath::new("src/error_0.py"), &error_content, 1);
    server.open_text_document(SystemPath::new("src/error_1.py"), &error_content, 1);
    server.open_text_document(SystemPath::new("src/error_2.py"), &error_content, 1);

    // First request to get result IDs (non-streaming for simplicity)
    let first_response = server.workspace_diagnostic_request(None)?;

    // Consume progress notifications from first request
    consume_all_progress_notifications(&mut server)?;

    let result_ids = extract_result_ids_from_response(&first_response);

    assert_eq!(result_ids.len(), NUM_FILES);

    // Fix three errors
    server.change_text_document(
        SystemPath::new("src/error_0.py"),
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: changed_content.to_string(),
        }],
        2,
    );

    server.change_text_document(
        SystemPath::new("src/error_1.py"),
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: changed_content.to_string(),
        }],
        2,
    );

    server.change_text_document(
        SystemPath::new("src/error_2.py"),
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: changed_content.to_string(),
        }],
        2,
    );

    // Second request with caching - use streaming to test the caching behavior
    let partial_token = lsp_types::ProgressToken::String("streaming-diagnostics".to_string());
    let request2_id =
        server.send_request::<WorkspaceDiagnosticRequest>(WorkspaceDiagnosticParams {
            identifier: None,
            previous_result_ids: result_ids,
            work_done_progress_params: WorkDoneProgressParams {
                work_done_token: None,
            },
            partial_result_params: PartialResultParams {
                partial_result_token: Some(partial_token.clone()),
            },
        });

    let final_response2 = server.await_response::<WorkspaceDiagnosticReportResult>(&request2_id)?;

    let mut all_items = Vec::new();

    // The final response should contain one fixed file and all unchanged files
    let items = match final_response2 {
        WorkspaceDiagnosticReportResult::Report(report) => report.items,
        WorkspaceDiagnosticReportResult::Partial(partial) => partial.items,
    };

    assert_eq!(items.len(), NUM_FILES - 3 + 1); // 3 fixed, 4 unchanged, 1 full report for fixed file

    all_items.extend(items);

    // Collect any partial results sent via progress notifications
    while let Ok(params) = server.await_notification::<PartialWorkspaceProgress>() {
        if params.token == partial_token {
            let streamed_items = match params.value {
                // Ideally we'd assert that only the first response is a full report
                // However, the type definition in the LSP specification is broken
                // in the sense that both `Report` and `Partial` have the exact same structure
                // but it also doesn't use a tag to tell them apart...
                // That means, a client can never tell if it's a full report or a partial report
                WorkspaceDiagnosticReportResult::Report(report) => report.items,
                WorkspaceDiagnosticReportResult::Partial(partial) => partial.items,
            };

            // All streamed batches should contain 2 items.
            assert_eq!(streamed_items.len(), 2);
            all_items.extend(streamed_items);

            if all_items.len() == NUM_FILES {
                break;
            }
        }
    }

    sort_workspace_report_items(&mut all_items);

    assert_debug_snapshot!(all_items);

    Ok(())
}

fn sort_workspace_diagnostic_response(response: &mut WorkspaceDiagnosticReportResult) {
    let items = match response {
        WorkspaceDiagnosticReportResult::Report(report) => &mut report.items,
        WorkspaceDiagnosticReportResult::Partial(partial) => &mut partial.items,
    };

    sort_workspace_report_items(items);
}

fn sort_workspace_report_items(items: &mut [WorkspaceDocumentDiagnosticReport]) {
    fn item_uri(item: &WorkspaceDocumentDiagnosticReport) -> &Url {
        match item {
            WorkspaceDocumentDiagnosticReport::Full(full_report) => &full_report.uri,
            WorkspaceDocumentDiagnosticReport::Unchanged(unchanged_report) => &unchanged_report.uri,
        }
    }

    items.sort_unstable_by(|a, b| item_uri(a).cmp(item_uri(b)));
}

/// The LSP specification requires that the server sends a response for every request.
///
/// This test verifies that the server responds to a long-polling workspace diagnostic request
/// when the server is shut down.
#[test]
fn workspace_diagnostic_long_polling_responds_on_shutdown() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let file_path = SystemPath::new("src/test.py");
    let file_content = "\
def hello() -> str:
    return \"world\"
";

    // Create a project with one file but no diagnostics
    let mut server = create_workspace_server_with_file(workspace_root, file_path, file_content)?;

    // Make a workspace diagnostic request to a project with one file but no diagnostics
    // This should trigger long-polling since the project has no diagnostics
    let request_id = send_workspace_diagnostic_request(&mut server);

    assert_workspace_diagnostics_suspends_for_long_polling(&mut server, &request_id);

    // Send shutdown request - this should cause the suspended workspace diagnostic request to respond
    let shutdown_id = server.send_request::<lsp_types::request::Shutdown>(());

    // The workspace diagnostic request should now respond with an empty report
    let workspace_response =
        server.await_response::<WorkspaceDiagnosticReportResult>(&request_id)?;

    // Complete shutdown sequence
    server.await_response::<()>(&shutdown_id)?;
    server.send_notification::<lsp_types::notification::Exit>(());

    // Verify we got an empty report (default response during shutdown)
    assert_debug_snapshot!(
        "workspace_diagnostic_long_polling_shutdown_response",
        workspace_response
    );

    Ok(())
}

/// Tests that the server responds to a long-polling workspace diagnostic request
/// after a change introduced a new diagnostic.
#[test]
fn workspace_diagnostic_long_polling_responds_on_change() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let file_path = SystemPath::new("src/test.py");
    let file_content_no_error = "\
def hello() -> str:
    return \"world\"
";
    let file_content_with_error = "\
def hello() -> str:
    return 42  # Type error: expected str, got int
";

    // Create a project with one file but no diagnostics
    let mut server =
        create_workspace_server_with_file(workspace_root, file_path, file_content_no_error)?;

    // Open the file first
    server.open_text_document(file_path, &file_content_no_error, 1);

    // Make a workspace diagnostic request to a project with one file but no diagnostics
    // This should trigger long-polling since the project has no diagnostics
    let request_id = send_workspace_diagnostic_request(&mut server);

    // Verify the request doesn't complete immediately (should be long-polling)
    assert_workspace_diagnostics_suspends_for_long_polling(&mut server, &request_id);

    // Now introduce an error to the file - this should trigger the long-polling request to complete
    server.change_text_document(
        file_path,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_content_with_error.to_string(),
        }],
        2,
    );

    // The workspace diagnostic request should now complete with the new diagnostic
    let workspace_response =
        server.await_response::<WorkspaceDiagnosticReportResult>(&request_id)?;

    // Verify we got a report with one file containing the new diagnostic
    assert_debug_snapshot!(
        "workspace_diagnostic_long_polling_change_response",
        workspace_response
    );

    Ok(())
}

/// The LSP specification requires that the server responds to each request with exactly one response.
///
/// This test verifies that the server sends one response (and not two) if a long polling workspace diagnostic request
/// is cancelled.
#[test]
fn workspace_diagnostic_long_polling_responds_on_cancellation() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let file_path = SystemPath::new("src/test.py");
    let file_content = "\
def hello() -> str:
    return \"world\"
";

    // Create a project with one file but no diagnostics
    let mut server = create_workspace_server_with_file(workspace_root, file_path, file_content)?;

    // Make a workspace diagnostic request to a project with one file but no diagnostics
    // This should trigger long-polling since the project has no diagnostics
    let request_id = send_workspace_diagnostic_request(&mut server);

    // Verify the request doesn't complete immediately (should be long-polling)
    assert_workspace_diagnostics_suspends_for_long_polling(&mut server, &request_id);

    // Send a cancel request notification for the suspended request
    // The request_id from send_request should match the ID that the server expects
    // Based on logs, the server shows request id=2, so let's try using that directly
    server.cancel(&request_id);

    // The workspace diagnostic request should now respond with a cancellation response (Err).
    let result = server.await_response::<WorkspaceDiagnosticReportResult>(&request_id);
    assert_debug_snapshot!(
        "workspace_diagnostic_long_polling_cancellation_result",
        result
    );

    // The test server's drop implementation asserts that we aren't sending the response twice.

    Ok(())
}

/// This test verifies an entire workspace diagnostic cycle with long-polling:
/// * Initial suspend with no diagnostics
/// * Change the file to introduce a diagnostic, server should respond with the new diagnostics
/// * Send a second workspace diagnostic request, which should suspend again because the diagnostics haven't changed
/// * Change the file again to fix the diagnostic, server should respond with no diagnostics
#[test]
fn workspace_diagnostic_long_polling_suspend_change_suspend_cycle() -> Result<()> {
    let _filter = filter_result_id();

    let workspace_root = SystemPath::new("src");
    let file_path = SystemPath::new("src/test.py");
    let file_content_no_error = "\
def hello() -> str:
    return \"world\"
";
    let file_content_with_error = "\
def hello() -> str:
    return 42  # Type error: expected str, got int
";
    let file_content_fixed = "\
def hello() -> str:
    return \"fixed\"
";

    // Create a project with one file but no diagnostics
    let mut server =
        create_workspace_server_with_file(workspace_root, file_path, file_content_no_error)?;

    // Open the file first
    server.open_text_document(file_path, &file_content_no_error, 1);

    // PHASE 1: Initial suspend (no diagnostics)
    let request_id_1 = send_workspace_diagnostic_request(&mut server);
    assert_workspace_diagnostics_suspends_for_long_polling(&mut server, &request_id_1);

    // PHASE 2: Introduce error to trigger response
    server.change_text_document(
        file_path,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_content_with_error.to_string(),
        }],
        2,
    );

    // First request should complete with diagnostics
    let first_response = server.await_response::<WorkspaceDiagnosticReportResult>(&request_id_1)?;

    // Extract result IDs from the first response for the second request
    let previous_result_ids = extract_result_ids_from_response(&first_response);

    // PHASE 3: Second request with previous result IDs - should suspend again since diagnostics unchanged
    let request_id_2 =
        server.send_request::<WorkspaceDiagnosticRequest>(WorkspaceDiagnosticParams {
            identifier: None,
            previous_result_ids,
            work_done_progress_params: WorkDoneProgressParams {
                work_done_token: None,
            },
            partial_result_params: PartialResultParams {
                partial_result_token: None,
            },
        });

    // Second request should suspend since diagnostics haven't changed
    assert_workspace_diagnostics_suspends_for_long_polling(&mut server, &request_id_2);

    // PHASE 4: Fix the error to trigger the second response
    server.change_text_document(
        file_path,
        vec![lsp_types::TextDocumentContentChangeEvent {
            range: None,
            range_length: None,
            text: file_content_fixed.to_string(),
        }],
        3,
    );

    // Second request should complete with the fix (no diagnostics)
    let second_response =
        server.await_response::<WorkspaceDiagnosticReportResult>(&request_id_2)?;

    // Snapshot both responses to verify the full cycle
    assert_debug_snapshot!(
        "workspace_diagnostic_suspend_change_suspend_first_response",
        first_response
    );
    assert_debug_snapshot!(
        "workspace_diagnostic_suspend_change_suspend_second_response",
        second_response
    );

    Ok(())
}

// Helper functions for long-polling tests
fn create_workspace_server_with_file(
    workspace_root: &SystemPath,
    file_path: &SystemPath,
    file_content: &str,
) -> Result<TestServer> {
    let global_options = ClientOptions::default().with_diagnostic_mode(DiagnosticMode::Workspace);

    TestServerBuilder::new()?
        .with_workspace(workspace_root, global_options.clone())?
        .with_file(file_path, file_content)?
        .with_initialization_options(global_options)
        .enable_pull_diagnostics(true)
        .build()?
        .wait_until_workspaces_are_initialized()
}

/// Sends a workspace diagnostic request to the server.
///
/// Unlike [`TestServer::workspace_diagnostic_request`], this function does not wait for the response.
fn send_workspace_diagnostic_request(server: &mut TestServer) -> lsp_server::RequestId {
    server.send_request::<WorkspaceDiagnosticRequest>(WorkspaceDiagnosticParams {
        identifier: None,
        previous_result_ids: Vec::new(),
        work_done_progress_params: WorkDoneProgressParams {
            work_done_token: None,
        },
        partial_result_params: PartialResultParams {
            partial_result_token: None,
        },
    })
}

#[track_caller]
fn assert_workspace_diagnostics_suspends_for_long_polling(
    server: &mut TestServer,
    request_id: &lsp_server::RequestId,
) {
    match server.await_response::<WorkspaceDiagnosticReportResult>(request_id) {
        Ok(_) => {
            panic!("Expected workspace diagnostic request to suspend for long-polling.");
        }
        Err(error) => {
            if let Some(test_error) = error.downcast_ref::<TestServerError>() {
                assert!(
                    matches!(test_error, TestServerError::RecvTimeoutError(_)),
                    "Response should time out because the request is suspended for long-polling"
                );
            } else {
                panic!("Unexpected error type: {error:?}");
            }
        }
    }
}

fn extract_result_ids_from_response(
    response: &WorkspaceDiagnosticReportResult,
) -> Vec<PreviousResultId> {
    match response {
        WorkspaceDiagnosticReportResult::Report(report) => {
            report
                .items
                .iter()
                .filter_map(|item| match item {
                    WorkspaceDocumentDiagnosticReport::Full(full_report) => {
                        let result_id = full_report
                            .full_document_diagnostic_report
                            .result_id
                            .as_ref()?;
                        Some(PreviousResultId {
                            uri: full_report.uri.clone(),
                            value: result_id.clone(),
                        })
                    }
                    WorkspaceDocumentDiagnosticReport::Unchanged(_) => {
                        // Unchanged reports don't provide new result IDs
                        None
                    }
                })
                .collect()
        }
        WorkspaceDiagnosticReportResult::Partial(partial) => {
            // For partial results, extract from items the same way
            partial
                .items
                .iter()
                .filter_map(|item| match item {
                    WorkspaceDocumentDiagnosticReport::Full(full_report) => {
                        let result_id = full_report
                            .full_document_diagnostic_report
                            .result_id
                            .as_ref()?;
                        Some(PreviousResultId {
                            uri: full_report.uri.clone(),
                            value: result_id.clone(),
                        })
                    }
                    WorkspaceDocumentDiagnosticReport::Unchanged(_) => None,
                })
                .collect()
        }
    }
}