fix(editor): re-add tester and prevent empty inverted diagnostics

crates/oxc_language_server/Cargo.toml

@@ -42,3 +42,6 @@ serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
 tokio = { workspace = true, features = ["rt-multi-thread", "io-std", "macros"] }
 tower-lsp = { workspace = true, features = ["proposed"] }
+
+[dev-dependencies]
+insta = { workspace = true }

crates/oxc_language_server/fixtures/linter/hello_world.js

@@ -0,0 +1 @@
+console.log("Hello, world!");

crates/oxc_language_server/fixtures/linter/issue_9958/.oxlintrc.json

@@ -0,0 +1,48 @@
+{
+  "env": {
+    "browser": true,
+    "node": true,
+    "es2022": true
+  },
+  "plugins": [
+    "node",
+    "eslint",
+    "oxc",
+    "unicorn",
+    // "import",
+    "typescript",
+    "react",
+    "react-perf",
+    "jsx-a11y",
+    "vitest",
+    "nextjs"
+  ],
+
+  "rules": {
+    "eqeqeq": "error",
+    "react/rules-of-hooks": "error",
+    "react/exhaustive-deps": "error",
+    "eslint/no-unused-vars": [
+      "error",
+      {
+        "varsIgnorePattern": "^_",
+        "argsIgnorePattern": "^_",
+        "caughtErrorsIgnorePattern": "^_",
+        "ignoreRestSiblings": true
+      }
+    ]
+  },
+  "categories": {
+    "correctness": "error"
+  },
+  "overrides": [
+    {
+      "files": ["**/*.spec.{ts,tsx,js,jsx}"],
+      "rules": {
+        "typescript/no-non-null-assertion": "off",
+        "typescript/no-non-null-asserted-optional-chain": "off"
+      }
+    }
+  ],
+  "ignorePatterns": ["e2e/**/*", "codemods/**/*", "scripts/**/*"]
+}

crates/oxc_language_server/fixtures/linter/issue_9958/issue.ts

@@ -0,0 +1,13 @@
+// Test case from https://github.com/oxc-project/oxc/issues/9958
+export function test() {
+  let x = true;
+  console.log(!!x ? 10 : 20);
+
+  let a: {
+    b?: {
+      c: number;
+    };
+  } = {};
+
+  console.log(a?.b?.c!);
+}

crates/oxc_language_server/src/linter/isolated_lint_handler.rs

@@ -65,6 +65,11 @@ impl IsolatedLintHandler {
                     if r.location.range == d.diagnostic.range {
                         continue;
                     }
+                    // If there is no message content for this span, then don't produce an additional diagnostic
+                    // which also has no content. This prevents issues where editors expect diagnostics to have messages.
+                    if r.message.is_empty() {
+                        continue;
+                    }
                     inverted_diagnostics.push(DiagnosticReport {
                         diagnostic: lsp_types::Diagnostic {
                             range: r.location.range,

crates/oxc_language_server/src/linter/mod.rs

@@ -5,6 +5,9 @@ pub mod error_with_position;
 mod isolated_lint_handler;
 pub mod server_linter;
 
+#[cfg(test)]
+mod tester;
+
 #[expect(clippy::cast_possible_truncation)]
 pub fn offset_to_position(offset: usize, source_text: &str) -> Position {
     // TODO(perf): share a single instance of `Rope`

crates/oxc_language_server/src/linter/server_linter.rs

@@ -28,3 +28,49 @@ impl ServerLinter {
             .run_single(&uri.to_file_path().unwrap(), content)
     }
 }
+
+#[cfg(test)]
+mod test {
+    use std::path::PathBuf;
+
+    use super::*;
+    use crate::linter::tester::Tester;
+    use oxc_linter::{LintFilter, LintFilterKind, Oxlintrc};
+
+    #[test]
+    fn test_no_errors() {
+        Tester::new()
+            .with_snapshot_suffix("no_errors")
+            .test_and_snapshot_single_file("fixtures/linter/hello_world.js");
+    }
+
+    #[test]
+    fn test_no_console() {
+        let config_store = ConfigStoreBuilder::default()
+            .with_filter(LintFilter::deny(LintFilterKind::parse("no-console".into()).unwrap()))
+            .build()
+            .unwrap();
+        let linter = Linter::new(LintOptions::default(), config_store).with_fix(FixKind::SafeFix);
+
+        Tester::new_with_linter(linter)
+            .with_snapshot_suffix("deny_no_console")
+            .test_and_snapshot_single_file("fixtures/linter/hello_world.js");
+    }
+
+    // Test case for https://github.com/oxc-project/oxc/issues/9958
+    #[test]
+    fn test_issue_9958() {
+        let config_store = ConfigStoreBuilder::from_oxlintrc(
+            true,
+            Oxlintrc::from_file(&PathBuf::from("fixtures/linter/issue_9958/.oxlintrc.json"))
+                .unwrap(),
+        )
+        .unwrap()
+        .build()
+        .unwrap();
+        let linter = Linter::new(LintOptions::default(), config_store).with_fix(FixKind::SafeFix);
+
+        Tester::new_with_linter(linter)
+            .test_and_snapshot_single_file("fixtures/linter/issue_9958/issue.ts");
+    }
+}

crates/oxc_language_server/src/linter/snapshots/fixtures_linter_hello_world.js@deny_no_console.snap

@@ -0,0 +1,13 @@
+---
+source: crates/oxc_language_server/src/linter/tester.rs
+---
+code: "eslint(no-console)"
+code_description.href: "https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-console"
+message: "eslint(no-console): Unexpected console statement.\nhelp: Delete this console statement."
+range: Range { start: Position { line: 0, character: 0 }, end: Position { line: 0, character: 11 } }
+related_information[0].message: ""
+related_information[0].location.uri: "file://<variable>/fixtures/linter/hello_world.js"
+related_information[0].location.range: Range { start: Position { line: 0, character: 0 }, end: Position { line: 0, character: 11 } }
+severity: Some(Error)
+source: Some("oxc")
+tags: None

crates/oxc_language_server/src/linter/snapshots/fixtures_linter_hello_world.js@no_errors.snap

@@ -0,0 +1,4 @@
+---
+source: crates/oxc_language_server/src/linter/tester.rs
+---
+No diagnostic reports

crates/oxc_language_server/src/linter/snapshots/fixtures_linter_issue_9958_issue.ts.snap

@@ -0,0 +1,28 @@
+---
+source: crates/oxc_language_server/src/linter/tester.rs
+---
+code: "eslint(no-extra-boolean-cast)"
+code_description.href: "https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-extra-boolean-cast"
+message: "Redundant double negation\nhelp: Remove the double negation as it will already be coerced to a boolean"
+range: Range { start: Position { line: 3, character: 14 }, end: Position { line: 3, character: 17 } }
+related_information[0].message: ""
+related_information[0].location.uri: "file://<variable>/fixtures/linter/issue_9958/issue.ts"
+related_information[0].location.range: Range { start: Position { line: 3, character: 14 }, end: Position { line: 3, character: 17 } }
+severity: Some(Error)
+source: Some("oxc")
+tags: None
+
+
+code: "typescript-eslint(no-non-null-asserted-optional-chain)"
+code_description.href: "https://oxc.rs/docs/guide/usage/linter/rules/typescript_eslint/no-non-null-asserted-optional-chain"
+message: "non-null assertions after an optional chain expression\nhelp: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion."
+range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 18 } }
+related_information[0].message: ""
+related_information[0].location.uri: "file://<variable>/fixtures/linter/issue_9958/issue.ts"
+related_information[0].location.range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 18 } }
+related_information[1].message: ""
+related_information[1].location.uri: "file://<variable>/fixtures/linter/issue_9958/issue.ts"
+related_information[1].location.range: Range { start: Position { line: 11, character: 21 }, end: Position { line: 11, character: 21 } }
+severity: Some(Error)
+source: Some("oxc")
+tags: None

crates/oxc_language_server/src/linter/tester.rs

@@ -0,0 +1,125 @@
+use oxc_linter::Linter;
+use tower_lsp::lsp_types::{CodeDescription, NumberOrString, Url};
+
+use super::{error_with_position::DiagnosticReport, server_linter::ServerLinter};
+
+/// Given a file path relative to the crate root directory, return the URI of the file.
+pub fn get_file_uri(relative_file_path: &str) -> Url {
+    let absolute_file_path =
+        std::env::current_dir().expect("could not get current dir").join(relative_file_path);
+    Url::from_file_path(absolute_file_path).expect("failed to convert file path to URL")
+}
+
+fn get_snapshot_from_report(report: &DiagnosticReport) -> String {
+    let code = match &report.diagnostic.code {
+        Some(NumberOrString::Number(code)) => code.to_string(),
+        Some(NumberOrString::String(code)) => code.to_string(),
+        None => "None".to_string(),
+    };
+    let code_description_href = match &report.diagnostic.code_description {
+        Some(CodeDescription { href }) => href.to_string(),
+        None => "None".to_string(),
+    };
+    let message = report.diagnostic.message.clone();
+    let range = report.diagnostic.range;
+    let related_information = match &report.diagnostic.related_information {
+        Some(infos) => {
+            infos
+                .iter()
+                .enumerate()
+                .map(|(i, info)| {
+                    let mut result = String::new();
+                    result.push_str(&format!(
+                        "related_information[{}].message: {:?}",
+                        i, info.message
+                    ));
+                    // replace everything between `file://` and `oxc_language_server` with `<variable>`, to avoid
+                    // the absolute path causing snapshot test failures in different environments
+                    let mut location = info.location.uri.to_string();
+                    let start =
+                        location.find("file://").expect("file:// protocol not found in URI");
+                    let end = location
+                        .find("oxc_language_server")
+                        .expect("oxc_language_server not found in URI");
+                    location.replace_range(
+                        start + "file://".len()..end + "oxc_language_server".len(),
+                        "<variable>",
+                    );
+
+                    result.push_str(&format!(
+                        "\nrelated_information[{i}].location.uri: {location:?}",
+                    ));
+                    result.push_str(&format!(
+                        "\nrelated_information[{}].location.range: {:?}",
+                        i, info.location.range
+                    ));
+                    result
+                })
+                .collect::<Vec<_>>()
+                .join("\n")
+        }
+        None => "related_information: None".to_string(),
+    };
+    let severity = report.diagnostic.severity;
+    let source = report.diagnostic.source.clone();
+    let tags = report.diagnostic.tags.clone();
+    format!(
+        r"
+code: {code:?}
+code_description.href: {code_description_href:?}
+message: {message:?}
+range: {range:?}
+{related_information}
+severity: {severity:?}
+source: {source:?}
+tags: {tags:?}
+            "
+    )
+}
+
+/// Testing struct for the [linter server][crate::linter::server_linter::ServerLinter].
+pub struct Tester<'t> {
+    server_linter: ServerLinter,
+    snapshot_suffix: Option<&'t str>,
+}
+
+impl Tester<'_> {
+    pub fn new() -> Self {
+        Self { snapshot_suffix: None, server_linter: ServerLinter::new() }
+    }
+
+    pub fn new_with_linter(linter: Linter) -> Self {
+        Self { snapshot_suffix: None, server_linter: ServerLinter::new_with_linter(linter) }
+    }
+
+    pub fn with_snapshot_suffix(mut self, suffix: &'static str) -> Self {
+        self.snapshot_suffix = Some(suffix);
+        self
+    }
+
+    /// Given a relative file path (relative to `oxc_language_server` crate root), run the linter
+    /// and return the resulting diagnostics in a custom snapshot format.
+    #[expect(clippy::disallowed_methods)]
+    pub fn test_and_snapshot_single_file(&self, relative_file_path: &str) {
+        let uri = get_file_uri(relative_file_path);
+        let content = std::fs::read_to_string(uri.to_file_path().unwrap())
+            .expect("could not read fixture file");
+        let reports = self.server_linter.run_single(&uri, Some(content)).unwrap();
+        let snapshot = if reports.is_empty() {
+            "No diagnostic reports".to_string()
+        } else {
+            reports.iter().map(get_snapshot_from_report).collect::<Vec<_>>().join("\n")
+        };
+
+        let snapshot_name = relative_file_path.replace('/', "_");
+        let mut settings = insta::Settings::clone_current();
+        settings.set_prepend_module_to_snapshot(false);
+        settings.set_omit_expression(true);
+        if let Some(suffix) = self.snapshot_suffix {
+            settings.set_snapshot_suffix(suffix);
+        }
+        settings.bind(|| {
+            insta::assert_snapshot!(snapshot_name, snapshot);
+        });
+    }
+}