fix: error if duplicate linters found

Author: suo

src/lint_config.rs

@@ -124,7 +124,17 @@ pub fn get_linters_from_config(
     config_path: &AbsPath,
 ) -> Result<Vec<Linter>> {
     let mut linters = Vec::new();
+    let mut all_linters: HashSet<String> = HashSet::new();
+
     for lint_config in linter_configs {
+        if all_linters.contains(&lint_config.code) {
+            bail!(
+                "Invalid linter configuration: linter '{}' is defined multiple times.",
+                lint_config.code
+            );
+        }
+        all_linters.insert(lint_config.code.clone());
+
         let include_patterns = patterns_from_strs(&lint_config.include_patterns)?;
         let exclude_patterns = if let Some(exclude_patterns) = &lint_config.exclude_patterns {
             patterns_from_strs(exclude_patterns)?
@@ -137,6 +147,7 @@ pub fn get_linters_from_config(
             "Invalid linter configuration: '{}' has an empty command list.",
             lint_config.code
         );
+
         linters.push(Linter {
             code: lint_config.code.clone(),
             include_patterns,
@@ -146,13 +157,8 @@ pub fn get_linters_from_config(
             config_path: config_path.clone(),
         });
     }
-    let all_linters = linters
-        .iter()
-        .map(|l| &l.code)
-        .cloned()
-        .collect::<HashSet<_>>();
 
-    debug!("Found linters: {:?}", all_linters,);
+    debug!("Found linters: {:?}", all_linters);
 
     // Apply --take
     if let Some(taken_linters) = taken_linters {

tests/integration_test.rs

@@ -204,6 +204,30 @@ fn simple_linter_fails_on_nonexistent_file() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn duplicate_code_fails() -> Result<()> {
+    let config = temp_config(
+        "\
+            [[linter]]
+            code = 'DUPE'
+            include_patterns = ['**']
+            command = ['wont_be_run']
+
+            [[linter]]
+            code = 'DUPE'
+            include_patterns = ['**']
+            command = ['wont_be_run']
+        ",
+    )?;
+
+    let mut cmd = Command::cargo_bin("lintrunner")?;
+    cmd.arg(format!("--config={}", config.path().to_str().unwrap()));
+    cmd.assert().failure();
+    assert_output_snapshot("duplicate_code_fails", &mut cmd)?;
+
+    Ok(())
+}
+
 #[test]
 fn linter_providing_nonexistent_path_degrades_gracefully() -> Result<()> {
     let data_path = tempfile::tempdir()?;

tests/snapshots/integration_test__duplicate_code_fails.snap

@@ -0,0 +1,10 @@
+---
+source: tests/integration_test.rs
+expression: output_lines
+---
+- "STDOUT:"
+- ""
+- ""
+- "STDERR:"
+- "error:        Invalid linter configuration: linter 'DUPE' is defined multiple times."
+