test(static inlined): pretty print the diff

Issue: rust-langGH-1090

Author: amanjeev

bindgen-tests/tests/tests.rs

@@ -742,7 +742,24 @@ fn test_extern_generated_headers() {
     let actual_h = fs::read_to_string(generated_path.join("extern.h"))
         .expect("Could not read actual extern.h");
 
-    assert_eq!(expected_c, actual_c);
-    assert_eq!(expected_h, actual_h);
+    if expected_c != actual_c {
+        error_diff_mismatch(
+            &actual_c,
+            &expected_c,
+            None,
+            Path::new(expect_path.join("extern.c").to_str().unwrap()),
+        )
+            .unwrap();
+    }
+
+    if expected_h != actual_h {
+        error_diff_mismatch(
+            &actual_h,
+            &expected_h,
+            None,
+            Path::new(expect_path.join("extern.h").to_str().unwrap()),
+        )
+            .unwrap();
+    }
 
 }