add unit test

tests/testsuite/clippy.rs

@@ -38,3 +38,37 @@ fn clippy_force_rebuild() {
         .with_stderr_contains("[..]assert!(true)[..]")
         .run();
 }
+
+#[cargo_test]
+fn clippy_passes_args() {
+    if !clippy_is_available() {
+        return;
+    }
+
+    // This is just a random clippy lint (assertions_on_constants) that
+    // hopefully won't change much in the future.
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [package]
+            name = "foo"
+            version = "0.1.0"
+
+            [dependencies]
+            "#,
+        )
+        .file("src/lib.rs", "pub fn f() { assert!(true); }")
+        .build();
+
+    p.cargo("clippy-preview -Zunstable-options -v -- -Aclippy::assertions_on_constants")
+        .masquerade_as_nightly_cargo()
+        .with_stderr_does_not_contain("[..]assert!(true)[..]")
+        .run();
+
+    // Make sure it runs again.
+    p.cargo("clippy-preview -Zunstable-options -v")
+        .masquerade_as_nightly_cargo()
+        .with_stderr_contains("[..]assert!(true)[..]")
+        .run();
+}