fix: dont panic when no linters are specified

Author: suo

src/lib.rs

@@ -165,6 +165,11 @@ pub fn do_lint(
         "Running linters: {:?}",
         linters.iter().map(|l| &l.code).collect::<Vec<_>>()
     );
+    let mut stdout = Term::stdout();
+    if linters.is_empty() {
+        stdout.write_line("No linters ran.")?;
+        return Ok(0);
+    }
 
     let mut files = match paths_opt {
         PathsOpt::Auto => {
@@ -261,8 +266,6 @@ pub fn do_lint(
     // Flush the logger before rendering results.
     log::logger().flush();
 
-    let mut stdout = Term::stdout();
-
     let did_print = match render_opt {
         RenderOpt::Default => render_lint_messages(&mut stdout, &all_lints)?,
         RenderOpt::Json => render_lint_messages_json(&mut stdout, &all_lints)?,

tests/integration_test.rs

@@ -878,3 +878,42 @@ fn linter_replacement_trailing_newlines() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn lint_with_no_linters() -> Result<()> {
+    let data_path = tempfile::tempdir()?;
+    let lint_message = LintMessage {
+        path: Some("tests/fixtures/fake_source_file.rs".to_string()),
+        line: Some(9),
+        char: Some(1),
+        code: "DUMMY".to_string(),
+        name: "dummy failure".to_string(),
+        severity: LintSeverity::Advice,
+        original: None,
+        replacement: None,
+        description: Some("A dummy linter failure".to_string()),
+    };
+    let config = temp_config(&format!(
+        "\
+            [[linter]]
+            code = 'TESTLINTER'
+            include_patterns = ['**']
+            command = ['echo', '{}']
+        ",
+        serde_json::to_string(&lint_message)?
+    ))?;
+
+    let mut cmd = Command::cargo_bin("lintrunner")?;
+    cmd.arg(format!("--config={}", config.path().to_str().unwrap()));
+    cmd.arg(format!(
+        "--data-path={}",
+        data_path.path().to_str().unwrap()
+    ));
+
+    // Run on a file to ensure that the linter is run.
+    cmd.arg("--skip=TESTLINTER");
+    cmd.assert().success();
+    assert_output_snapshot("lint_with_no_linters", &mut cmd)?;
+
+    Ok(())
+}

tests/snapshots/integration_test__format_command_doesnt_use_nonformat_linter.snap

@@ -1,11 +1,9 @@
 ---
 source: tests/integration_test.rs
-assertion_line: 20
 expression: output_lines
 ---
 - "STDOUT:"
-- ok No lint issues.
-- Successfully applied all patches.
+- No linters ran.
 - ""
 - ""
 - "STDERR:"