From 4f4e249a042d4fb0365c588b6550ad3ae0ccf268 Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrusn@microsoft.com>
Date: Mon, 8 Dec 2014 14:03:31 -0800
Subject: [PATCH] Add tree invariant checking to the test262 runner.

---
 src/harness/test262Runner.ts | 45 ++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/src/harness/test262Runner.ts b/src/harness/test262Runner.ts
index 756ff82ef97..fa4dc14e213 100644
--- a/src/harness/test262Runner.ts
+++ b/src/harness/test262Runner.ts
@@ -21,6 +21,38 @@ class Test262BaselineRunner extends RunnerBase {
         return Test262BaselineRunner.basePath + "/" + filename;
     }
 
+    private static checkInvariants(node: ts.Node, parent: ts.Node): void {
+        if (node) {
+            if (node.pos < 0) {
+                throw new Error("node.pos < 0");
+            }
+            if (node.end < 0) {
+                throw new Error("node.end < 0");
+            }
+            if (node.end < node.pos) {
+                throw new Error("node.end < node.pos");
+            }
+            if (node.parent !== parent) {
+                throw new Error("node.parent !== parent");
+            }
+            ts.forEachChild(node, child => {
+                Test262BaselineRunner.checkInvariants(child, node);
+            });
+
+            var childNodesAndArrays: any[] = [];
+            ts.forEachChild(node, child => { childNodesAndArrays.push(child) }, array => { childNodesAndArrays.push(array) });
+
+            for (var childName in node) {
+                var child = (<any>node)[childName];
+                if (Test262BaselineRunner.isNodeOrArray(child)) {
+                    if (childNodesAndArrays.indexOf(child) < 0) {
+                        throw new Error("Child when forEach'ing over node. " + (<any>ts).SyntaxKind[node.kind] + "-" + childName);
+                    }
+                }
+            }
+        }
+    }
+
     private static serializeSourceFile(file: ts.SourceFile): string {
         function getKindName(k: number): string {
             return (<any>ts).SyntaxKind[k]
@@ -89,11 +121,15 @@ class Test262BaselineRunner extends RunnerBase {
             return o;
         }
 
-        return JSON.stringify(file,(k, v) => {
-            return (v && typeof v.pos === "number") ? serializeNode(v) : v;
+        return JSON.stringify(file, (k, v) => {
+            return Test262BaselineRunner.isNodeOrArray(v) ? serializeNode(v) : v;
         }, "    ");
     }
 
+    private static isNodeOrArray(a: any): boolean {
+        return a !== undefined && typeof a.pos === "number";
+    }
+
     private runTest(filePath: string) {
         describe('test262 test for ' + filePath, () => {
             // Mocha holds onto the closure environment of the describe callback even after the test is done.
@@ -150,6 +186,11 @@ class Test262BaselineRunner extends RunnerBase {
                 }, false, Test262BaselineRunner.baselineOptions);
             });
 
+            it('satisfies invariants', () => {
+                var sourceFile = testState.checker.getProgram().getSourceFile(Test262BaselineRunner.getTestFilePath(testState.filename));
+                Test262BaselineRunner.checkInvariants(sourceFile, /*parent:*/ undefined);
+            });
+
             it('has the expected AST',() => {
                 Harness.Baseline.runBaseline('has the expected AST', testState.filename + '.AST.txt',() => {
                     var sourceFile = testState.checker.getProgram().getSourceFile(Test262BaselineRunner.getTestFilePath(testState.filename));