enable esprima tests for iterators

Summary: flow supports for-of but the esprima tests were disabled.

one of the cases (`for (var x = 42 of list)`) fails in flow but passes in esprima-fb 15001.1.0-dev-harmony-fb. afaict, it's fixed in upstream esprima so we can delete the expected difference once we merge/upgrade.

also, turns out that the esprima test runner doesn't handle the case where we error but esprima doesn't. fixed that by making it generate diffs for the errors so that we can expect them.

Reviewed By: @gabelevi

Differential Revision: D2193570

src/parser/test/esprima_test_runner.js

@@ -57,7 +57,8 @@ function new_env() {
 
 function diff_to_string(diff) {
   var expected_str = "";
-  if (typeof diff.expected !== "undefined") {
+  if (typeof diff.expected !== "undefined" ||
+      typeof diff.actual !== "undefined") {
     expected_str =
       ". Expected " + diff.expected + ", got " + diff.actual;
   }
@@ -393,17 +394,21 @@ function runTest(test, esprima_opts) {
     compare(esprima_ast, flow_ast, env);
 
     if (flow_errors.length !== 0) {
-      result.passed = false;
-      output("****Unexpected Errors****");
+      env.push_path('errors');
       for (var i = 0; i < flow_errors.length; i++) {
         var e = flow_errors[i];
-        output(
-          "(#" + i + ")",
-          "(line " + e.loc.start.line + ", col " + e.loc.start.column + ") - " +
-          "(line " + e.loc.end.line + ", col " + e.loc.end.column + "): ",
-          e.message
-        );
+        env.push_path(i);
+        env.push_path('column');
+        env.diff("Wrong error column", undefined, e.loc.start.column + 1);
+        env.pop_path();
+        env.push_path('line');
+        env.diff("Wrong error line", undefined, e.loc.start.line);
+        env.pop_path();
+        env.push_path('message');
+        env.diff("Wrong error message", undefined, e.message);
+        env.pop_path();
       }
+      env.pop_path();
     }
 
     var ast_types_errors = env.get_ast_types_errors();

src/parser/test/esprima_tests.js

@@ -4154,8 +4154,28 @@ module.exports = {
     'Harmony: Iterators': [
         'for(x of list) process(x);',
         'for (var x of list) process(x);',
-        'for (var x = 42 of list) process(x);',
-        'for (let x of list) process(x);'
+        'for (let x of list) process(x);',
+        {
+          content: 'for (var x = 42 of list) process(x);',
+          explanation: "Esprima thinks this is valid, it isn't",
+          expected_differences : {
+            'root.errors.0.column': {
+              type: 'Wrong error column',
+              expected: undefined,
+              actual: 6,
+            },
+            'root.errors.0.line': {
+              type: 'Wrong error line',
+              expected: undefined,
+              actual: 1,
+            },
+            'root.errors.0.message': {
+              type: 'Wrong error message',
+              expected: undefined,
+              actual: 'Invalid left-hand side in for-of',
+            }
+          }
+        }
     ],
 
 

src/parser/test/run_esprima_tests.js

@@ -11,7 +11,6 @@ var todo = {
   'Invalid Type Annotations': true,
   'Array Comprehension': true,
   'Harmony: Modules': true,
-  'Harmony: Iterators': true,
   'Harmony: Invalid Class (strawman)': true,
   'ES6: Destructured Parameters': true,
   'ES7 Proposal: Rest Properties' : true,