test(test2): Add UI tests for macro error output

The tests use the `trybuild` crate to check that compilation
fails for the incorrect macro use. The test will also fail
if the error output changes.

These were added directly to the `tests` directory
(as opposed to being part of the `testsuite` subdirectory)
because the automatic check and overwrite functionality 
provided by the `trybuild` crate seemed to not work properly
when placed there.

Author: skogseth

Cargo.lock

@@ -39,6 +39,7 @@ escargot = "0.5.8"
 once_cell_polyfill = "1.56.0"
 pathdiff = "0.2.1"
 snapbox = { version = "0.6.0", features = ["json"] }
+trybuild = "1.0.111"
 
 [lints]
 workspace = true

crates/libtest2/Cargo.toml

@@ -0,0 +1,5 @@
+#[test]
+fn ui() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/ui/*.rs");
+}

crates/libtest2/tests/ui.rs

@@ -0,0 +1,8 @@
+#[libtest2::main]
+fn main() {}
+
+#[libtest2::test]
+#[ignore(reason = "invalid syntax right here")]
+fn test(_: &libtest2::TestContext) {
+    panic!("We just need to compile this");
+}

crates/libtest2/tests/ui/ignore_incorrect_usage.rs

@@ -0,0 +1,7 @@
+error: unknown attribute 'ignore(reason = "invalid syntax right here")'
+ --> tests/ui/ignore_incorrect_usage.rs:4:1
+  |
+4 | #[libtest2::test]
+  | ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the macro `$crate::_private::test_parse` which comes from the expansion of the attribute macro `libtest2::test` (in Nightly builds, run with -Z macro-backtrace for more info)

crates/libtest2/tests/ui/ignore_incorrect_usage.stderr

@@ -0,0 +1,8 @@
+#[libtest2::main]
+fn main() {}
+
+#[libtest2::test]
+#[should_panic(expect = "something")]
+fn test(_: &libtest2::TestContext) {
+    panic!("the correct attribute is 'expected = \"...\"'");
+}

crates/libtest2/tests/ui/should_panic_attribute_typo.rs

@@ -0,0 +1,7 @@
+error: unknown attribute 'should_panic(expect = "something")'
+ --> tests/ui/should_panic_attribute_typo.rs:4:1
+  |
+4 | #[libtest2::test]
+  | ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the macro `$crate::_private::test_parse` which comes from the expansion of the attribute macro `libtest2::test` (in Nightly builds, run with -Z macro-backtrace for more info)

crates/libtest2/tests/ui/should_panic_attribute_typo.stderr

@@ -0,0 +1,17 @@
+#[libtest2::main]
+fn main() {}
+
+#[libtest2::test]
+#[should_panic]
+#[should_panic]
+fn test_1(_: &libtest2::TestContext) {}
+
+#[libtest2::test]
+#[should_panic]
+#[should_panic(reason = "something")]
+fn test_2(_: &libtest2::TestContext) {}
+
+#[libtest2::test]
+#[should_panic = "anything"]
+#[should_panic]
+fn test_3(_: &libtest2::TestContext) {}

crates/libtest2/tests/ui/should_panic_multiple_attributes.rs

@@ -0,0 +1,23 @@
+error: annotating a test with multiple 'should_panic' attributes is not allowed
+ --> tests/ui/should_panic_multiple_attributes.rs:4:1
+  |
+4 | #[libtest2::test]
+  | ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the macro `$crate::_private::test_parse` which comes from the expansion of the attribute macro `libtest2::test` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: annotating a test with multiple 'should_panic' attributes is not allowed
+ --> tests/ui/should_panic_multiple_attributes.rs:9:1
+  |
+9 | #[libtest2::test]
+  | ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the macro `$crate::_private::test_parse` which comes from the expansion of the attribute macro `libtest2::test` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: annotating a test with multiple 'should_panic' attributes is not allowed
+  --> tests/ui/should_panic_multiple_attributes.rs:14:1
+   |
+14 | #[libtest2::test]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: this error originates in the macro `$crate::_private::test_parse` which comes from the expansion of the attribute macro `libtest2::test` (in Nightly builds, run with -Z macro-backtrace for more info)

crates/libtest2/tests/ui/should_panic_multiple_attributes.stderr

@@ -0,0 +1,6 @@
+#[libtest2::main]
+fn main() {}
+
+#[libtest2::test]
+#[unsafe(no_mangle)] // we just need some unknown attribute here
+fn test(_: &libtest2::TestContext) {}