feat(test2): Allow use of custom error types

Author: epage

crates/libtest2-harness/src/error.rs

@@ -80,3 +80,12 @@ impl IntoRunResult for RunResult {
         self
     }
 }
+
+impl<E> IntoRunResult for Result<(), E>
+where
+    E: std::error::Error + Send + Sync + 'static,
+{
+    fn into_run_result(self) -> RunResult {
+        self.map_err(RunError::with_cause)
+    }
+}

crates/libtest2/tests/testsuite/mixed_bag.rs

@@ -65,8 +65,8 @@ fn horse(context: &libtest2::TestContext) {
 }
 
 #[libtest2::test]
-fn custom_error(context: &libtest2::TestContext) -> libtest2::RunResult {
-    Err(libtest2::RunError::from(std::io::Error::new(std::io::ErrorKind::Other, "I failed")))
+fn custom_error(context: &libtest2::TestContext) -> std::io::Result<()> {
+    Err(std::io::Error::new(std::io::ErrorKind::Other, "I failed"))
 }
 
 "#,