test: add test case for highlight unsafe operations

Author: gohome001

src/tools/rust-analyzer/crates/ide/src/highlight_related.rs

@@ -811,6 +811,34 @@ mod tests {
         assert_eq!(expected, actual);
     }
 
+    #[test]
+    fn test_hl_unsafe_block() {
+        check(
+            r#"
+fn foo() {
+    unsafe fn this_is_unsafe_function() {
+    }
+
+    
+    unsa$0fe {
+  //^^^^^^
+        let raw_ptr = &42 as *const i32;
+        let val = *raw_ptr;
+                //^^^^^^^^
+        
+        let mut_ptr = &mut 5 as *mut i32;
+        *mut_ptr = 10;
+      //^^^^^^^^
+        
+        this_is_unsafe_function();
+      //^^^^^^^^^^^^^^^^^^^^^^^^^
+    }
+    
+}
+"#,
+        );
+    }
+
     #[test]
     fn test_hl_tuple_fields() {
         check(