Add tests that show existing behavior

tests/testsuite/main.rs

@@ -182,6 +182,7 @@ mod vendor;
 mod verify_project;
 mod version;
 mod warn_on_failure;
+mod warning_override;
 mod weak_dep_features;
 mod workspaces;
 mod yank;

tests/testsuite/warning_override.rs

@@ -0,0 +1,182 @@
+//! Tests for overriding warning behavior using `build.warnings` config option.
+
+use cargo_test_support::{cargo_test, project, str, tools, Project};
+
+fn make_project_with_rustc_warning() -> Project {
+    project()
+        .file(
+            "Cargo.toml",
+            &format!(
+                r#"
+                [package]
+                name = "foo"
+                version = "0.0.1"
+                edition = "2021"
+            "#
+            ),
+        )
+        .file("src/main.rs", "fn main() { let x = 3; }")
+        .build()
+}
+
+#[cargo_test]
+fn rustc_caching_allow_first() {
+    let p = make_project_with_rustc_warning();
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[CHECKING] foo v0.0.1 ([ROOT]/foo)
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn rustc_caching_deny_first() {
+    let p = make_project_with_rustc_warning();
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[CHECKING] foo v0.0.1 ([ROOT]/foo)
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn config() {
+    let p = make_project_with_rustc_warning();
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[CHECKING] foo v0.0.1 ([ROOT]/foo)
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+
+    // CLI has precedence over env
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn requires_nightly() {
+    // build.warnings has no effect without -Zwarnings.
+    let p = make_project_with_rustc_warning();
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[CHECKING] foo v0.0.1 ([ROOT]/foo)
+[WARNING] unused variable: `x`
+ --> src/main.rs:1:17
+  |
+1 | fn main() { let x = 3; }
+  |                 ^ [HELP] if this is intentional, prefix it with an underscore: `_x`
+  |
+  = [NOTE] `#[warn(unused_variables)]` on by default
+
+[WARNING] `foo` (bin "foo") generated 1 warning
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}
+
+#[cargo_test]
+fn clippy() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.0.1"
+                edition = "2015"
+            "#,
+        )
+        .file("src/lib.rs", "use std::io;") // <-- unused import
+        .build();
+
+    p.cargo("check")
+        .env("RUSTC_WORKSPACE_WRAPPER", tools::wrapped_clippy_driver())
+        .with_stderr_data(str![[r#"
+[CHECKING] foo v0.0.1 ([ROOT]/foo)
+[WARNING] unused import: `std::io`
+...
+[WARNING] `foo` (lib) generated 1 warning (run `cargo clippy --fix --lib -p foo` to apply 1 suggestion)
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}