Fix crate_wide_allow

examples/general/crate_wide_allow/src/lib.rs

@@ -72,13 +72,32 @@ mod test {
     use cargo_metadata::MetadataCommand;
     use dylint_internal::env;
     use predicates::prelude::*;
-    use std::{env::consts, sync::Mutex};
+    use std::{
+        env::consts,
+        sync::{Mutex, MutexGuard},
+    };
 
-    static MUTEX: Mutex<()> = Mutex::new(());
+    fn mutex(keep: bool) -> Option<MutexGuard<'static, ()>> {
+        static MUTEX: Mutex<()> = Mutex::new(());
+
+        let lock = MUTEX.lock().unwrap();
+
+        // smoelius: Ensure the `clippy` component is installed.
+        Command::new("rustup")
+            .args(["component", "add", "clippy"])
+            .assert()
+            .success();
+
+        if keep {
+            Some(lock)
+        } else {
+            None
+        }
+    }
 
     #[test]
     fn ui() {
-        let _lock = MUTEX.lock().unwrap();
+        let _lock = mutex(true);
 
         dylint_testing::ui_test_example(env!("CARGO_PKG_NAME"), "ui");
     }
@@ -115,7 +134,7 @@ mod test {
     fn test(rustflags: &str, assert: impl Fn(Assert) -> Assert) {
         const MANIFEST_DIR: &str = "../../..";
 
-        let _lock = MUTEX.lock().unwrap();
+        let _lock = mutex(true);
 
         Command::new("cargo")
             .current_dir(MANIFEST_DIR)
@@ -159,6 +178,8 @@ mod test {
 
     #[test]
     fn premise_manifest_sanity() {
+        mutex(false);
+
         let mut command = Command::new("cargo");
         command.args(["clippy"]);
         command.current_dir("ui_manifest");
@@ -171,6 +192,8 @@ mod test {
     /// Verify that `allow`ing a lint in the manifest does not silently override `--warn`.
     #[test]
     fn premise_manifest_warn() {
+        mutex(false);
+
         let mut command = Command::new("cargo");
         command.args(["clippy", "--", "--warn=clippy::assertions-on-constants"]);
         command.current_dir("ui_manifest");
@@ -183,6 +206,8 @@ mod test {
     /// Verify that `allow`ing a lint in the manifest does not silently override `--deny`.
     #[test]
     fn premise_manifest_deny() {
+        mutex(false);
+
         let mut command = Command::new("cargo");
         command.args(["clippy", "--", "--deny=clippy::assertions-on-constants"]);
         command.current_dir("ui_manifest");