Capture names as full paths (#165)

The tests emitted by rustc use the full path, not including the crate
name, as the name for the test
([impl](https://github.com/rust-lang/rust/blob/ec6f62244c3a019e2224b779d2b606721cabf8f2/compiler/rustc_builtin_macros/src/test.rs#L66)).
From what I can tell there's no way to get this path exactly from rust,
but we can get the full path including crate name from
[`std::module_path`](https://doc.rust-lang.org/std/macro.module_path.html).
We can then find the first occurence of `::` and grab whatever follows.

Fixes #154.

Author: epage

crates/libtest2/src/macros.rs

@@ -110,7 +110,9 @@ macro_rules! _test_parse {
             fn name(&self) -> &str {
                 $crate::_private::push!(crate::TESTS, _: $crate::_private::DynCase = $crate::_private::DynCase(&$name));
 
-                stringify!($name)
+                const FULL_PATH: &str = concat!(std::module_path!(), "::", stringify!($name));
+                let i = FULL_PATH.find("::").expect("we have inserted this in the line above so it must be there");
+                &FULL_PATH[(i+2)..]
             }
             fn kind(&self) -> $crate::_private::TestKind {
                 Default::default()

crates/libtest2/tests/testsuite/macros.rs

@@ -0,0 +1,46 @@
+use snapbox::str;
+
+fn test_cmd() -> snapbox::cmd::Command {
+    static BIN: once_cell_polyfill::sync::OnceLock<(std::path::PathBuf, std::path::PathBuf)> =
+        once_cell_polyfill::sync::OnceLock::new();
+    let (bin, current_dir) = BIN.get_or_init(|| {
+        let package_root = crate::util::new_test(
+            r#"
+#[libtest2::main]
+fn main() {}
+
+#[libtest2::test]
+fn foo(_context: &libtest2::TestContext) {}
+
+mod some_module {
+    #[libtest2::test]
+    fn foo(_context: &libtest2::TestContext) {}
+}
+"#,
+            false,
+        );
+        let bin = crate::util::compile_test(&package_root);
+        (bin, package_root)
+    });
+    snapbox::cmd::Command::new(bin).current_dir(current_dir)
+}
+
+#[test]
+fn check() {
+    let data = str![[r#"
+
+running 2 tests
+test foo              ... ok
+test some_module::foo ... ok
+
+test result: ok. 2 passed; 0 failed; 0 ignored; 0 filtered out; finished in [..]s
+
+
+"#]];
+
+    test_cmd()
+        .args(["--test-threads", "1"])
+        .assert()
+        .success()
+        .stdout_eq(data);
+}

crates/libtest2/tests/testsuite/main.rs

@@ -1,5 +1,6 @@
 mod all_passing;
 mod argfile;
+mod macros;
 mod mixed_bag;
 mod panic;
 mod should_panic;