Add mdtest support for files with invalid syntax (#14126)

crates/red_knot_python_semantic/resources/mdtest/exception/invalid_exception_syntax.md

@@ -0,0 +1,13 @@
+# Exception Handling
+
+## Invalid syntax
+
+```py
+from typing_extensions import reveal_type
+
+try:
+    print
+except as e:  # error: [invalid-syntax]
+    reveal_type(e)  # revealed: Unknown
+
+```

crates/red_knot_python_semantic/src/types/diagnostic.rs

@@ -8,7 +8,7 @@ use std::sync::Arc;
 use crate::types::{ClassLiteralType, Type};
 use crate::Db;
 
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Debug, Eq, PartialEq, Clone)]
 pub struct TypeCheckDiagnostic {
     // TODO: Don't use string keys for rules
     pub(super) rule: String,

crates/red_knot_python_semantic/src/types/infer.rs

@@ -5061,27 +5061,6 @@ mod tests {
         Ok(())
     }
 
-    #[test]
-    fn exception_handler_with_invalid_syntax() -> anyhow::Result<()> {
-        let mut db = setup_db();
-
-        db.write_dedented(
-            "src/a.py",
-            "
-            from typing_extensions import reveal_type
-
-            try:
-                print
-            except as e:
-                reveal_type(e)
-            ",
-        )?;
-
-        assert_file_diagnostics(&db, "src/a.py", &["Revealed type is `Unknown`"]);
-
-        Ok(())
-    }
-
     #[test]
     fn basic_comprehension() -> anyhow::Result<()> {
         let mut db = setup_db();
@@ -5424,7 +5403,7 @@ mod tests {
                     return 42
 
             class Iterable:
-                def __iter__(self) -> Iterator:
+                def __iter__(self) -> Iterator: ...
 
             x = [*NotIterable()]
             y = [*Iterable()]