Extract Translator struct

compiler/rustc_errors/src/json/tests.rs

@@ -41,14 +41,14 @@ fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
     rustc_span::create_default_session_globals_then(|| {
         let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
         sm.new_source_file(Path::new("test.rs").to_owned().into(), code.to_owned());
-        let fallback_bundle =
-            crate::fallback_fluent_bundle(vec![crate::DEFAULT_LOCALE_RESOURCE], false);
+        let translator =
+            Translator::with_fallback_bundle(vec![crate::DEFAULT_LOCALE_RESOURCE], false);
 
         let output = Arc::new(Mutex::new(Vec::new()));
         let je = JsonEmitter::new(
             Box::new(Shared { data: output.clone() }),
             Some(sm),
-            fallback_bundle,
+            translator,
             true, // pretty
             HumanReadableErrorType::Short,
             ColorConfig::Never,