Auto merge of #13880 - Muscraft:refactor-cargo-lint-tests, r=<try>

Refactor cargo lint tests

In #13621, it was brought up that [the lints tests are nested more deeply than other UI tests](#13621 (comment)). This got me wondering if there was a better way to structure all the lint tests.
What I came up with was:
- Lints should not have UI tests, only parts of the diagnostic system, i.e., how warnings, errors, notes, etc., look
  - This is because UI tests should focus on parts of the system that make up each lint's output
  - We can always add UI tests for each lint if desired
- All tests related to the linting system should live in `tests/testsuite/lints/`
- Tests related to `[lints.cargo]` should stay in `lints_table.rs` as it is for the whole lints table
- Each lint will get a file in `lints/` for all of its tests
  - This makes `lints/mod.rs` smaller and targeted only at tests for the linting system itself
  - It makes it much easier to know where to place a test

tests/testsuite/lints/unused_optional_dependencies/edition_2021/mod.rs → tests/testsuite/lints/error/mod.rs

@@ -1,37 +1,36 @@
 use cargo_test_support::prelude::*;
-use cargo_test_support::project;
-use cargo_test_support::registry::Package;
-use cargo_test_support::{file, str};
+use cargo_test_support::str;
+use cargo_test_support::{file, project};
 
 #[cargo_test]
 fn case() {
-    Package::new("bar", "0.1.0").publish();
     let p = project()
         .file(
             "Cargo.toml",
             r#"
+cargo-features = ["test-dummy-unstable"]
+
 [package]
 name = "foo"
-version = "0.1.0"
-edition = "2021"
-
-[dependencies]
-bar = { version = "0.1.0", optional = true }
+version = "0.0.1"
+edition = "2015"
+authors = []
+im-a-teapot = true
 
 [lints.cargo]
-implicit_features = "allow"
-"#,
+im_a_teapot = "deny"
+            "#,
         )
         .file("src/lib.rs", "")
         .build();
 
     snapbox::cmd::Command::cargo_ui()
-        .masquerade_as_nightly_cargo(&["cargo-lints"])
+        .masquerade_as_nightly_cargo(&["cargo-lints", "test-dummy-unstable"])
         .current_dir(p.root())
         .arg("check")
         .arg("-Zcargo-lints")
         .assert()
-        .success()
+        .code(101)
         .stdout_matches(str![""])
         .stderr_matches(file!["stderr.term.svg"]);
 }

tests/testsuite/lints/implicit_features.rs

@@ -0,0 +1,137 @@
+use cargo_test_support::project;
+use cargo_test_support::registry::Package;
+
+#[cargo_test]
+fn default() {
+    Package::new("bar", "0.1.0").publish();
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+[package]
+name = "foo"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+bar = { version = "0.1.0", optional = true }
+"#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("check -Zcargo-lints")
+        .masquerade_as_nightly_cargo(&["cargo-lints"])
+        .with_stderr(
+            "\
+[UPDATING] [..]
+[LOCKING] 2 packages to latest compatible versions
+[CHECKING] foo v0.1.0 ([CWD])
+[FINISHED] [..]
+",
+        )
+        .run();
+}
+
+#[cargo_test]
+fn warn() {
+    Package::new("bar", "0.1.0").publish();
+    Package::new("baz", "0.1.0").publish();
+    Package::new("target-dep", "0.1.0").publish();
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+[package]
+name = "foo"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+bar = { version = "0.1.0", optional = true }
+
+[build-dependencies]
+baz = { version = "0.1.0", optional = true }
+
+[target.'cfg(target_os = "linux")'.dependencies]
+target-dep = { version = "0.1.0", optional = true }
+
+[lints.cargo]
+implicit_features = "warn"
+"#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("check -Zcargo-lints")
+        .masquerade_as_nightly_cargo(&["cargo-lints"])
+        .with_stderr(
+            "\
+warning: implicit features for optional dependencies is deprecated and will be unavailable in the 2024 edition
+ --> Cargo.toml:8:1
+  |
+8 | bar = { version = \"0.1.0\", optional = true }
+  | ---
+  |
+  = note: `cargo::implicit_features` is set to `warn` in `[lints]`
+warning: implicit features for optional dependencies is deprecated and will be unavailable in the 2024 edition
+  --> Cargo.toml:11:1
+   |
+11 | baz = { version = \"0.1.0\", optional = true }
+   | ---
+   |
+warning: implicit features for optional dependencies is deprecated and will be unavailable in the 2024 edition
+  --> Cargo.toml:14:1
+   |
+14 | target-dep = { version = \"0.1.0\", optional = true }
+   | ----------
+   |
+[UPDATING] [..]
+[LOCKING] 4 packages to latest compatible versions
+[CHECKING] foo v0.1.0 ([CWD])
+[FINISHED] [..]
+",
+        )
+        .run();
+}
+
+#[cargo_test(nightly, reason = "edition2024 is not stable")]
+fn implicit_features_edition_2024() {
+    Package::new("bar", "0.1.0").publish();
+    Package::new("baz", "0.1.0").publish();
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+cargo-features = ["edition2024"]
+[package]
+name = "foo"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+bar = { version = "0.1.0", optional = true }
+baz = { version = "0.1.0", optional = true }
+
+[features]
+baz = ["dep:baz"]
+
+[lints.cargo]
+unused_optional_dependency = "allow"
+"#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("check -Zcargo-lints")
+        .masquerade_as_nightly_cargo(&["cargo-lints", "edition2024"])
+        .with_stderr(
+            "\
+[UPDATING] [..]
+[LOCKING] 2 packages to latest Rust [..] compatible versions
+[CHECKING] foo v0.1.0 ([CWD])
+[FINISHED] [..]
+",
+        )
+        .run();
+}