Bug 1657509 - Always resolve ReadableStream's tee()'s cancel promise …

…after the stream closes or errors. r=arai

Seems like the existing step numbers refer to a differently formatted spec. I updated the numbers
where I changed something to match https://streams.spec.whatwg.org/.

Differential Revision: https://phabricator.services.mozilla.com/D109237

js/src/builtin/streams/ReadableStreamOperations.cpp

@@ -213,32 +213,38 @@ static bool TeeReaderReadHandler(JSContext* cx, unsigned argc, Value* vp) {
     done = doneVal.toBoolean();
   }
 
-  // Step 12.c.v: If done is true,
   if (done) {
-    // Step 12.c.v.1: If canceled1 is false,
+    // Step 12.3 close steps
+
+    // Step 1: Set reading to false (done unconditionally above).
+    // Step 2: If canceled1 is false, perform
+    //         ! ReadableStreamDefaultControllerClose(branch1.[[controller]]).
     if (!unwrappedTeeState->canceled1()) {
-      // Step 12.c.v.1.a: Perform
-      //                  ! ReadableStreamDefaultControllerClose(
-      //                        branch1.[[readableStreamController]]).
       Rooted<ReadableStreamDefaultController*> unwrappedBranch1(
           cx, unwrappedTeeState->branch1());
       if (!ReadableStreamDefaultControllerClose(cx, unwrappedBranch1)) {
         return false;
       }
     }
 
-    // Step 12.c.v.2: If canceled2 is false,
+    // Step 3: If canceled2 is false, perform
+    //         ! ReadableStreamDefaultControllerClose(branch2.[[controller]]).
     if (!unwrappedTeeState->canceled2()) {
-      // Step 12.c.v.2.a: Perform
-      //                  ! ReadableStreamDefaultControllerClose(
-      //                        branch2.[[readableStreamController]]).
       Rooted<ReadableStreamDefaultController*> unwrappedBranch2(
           cx, unwrappedTeeState->branch2());
       if (!ReadableStreamDefaultControllerClose(cx, unwrappedBranch2)) {
         return false;
       }
     }
 
+    // Step 4: Resolve cancelPromise with undefined.
+    Rooted<PromiseObject*> unwrappedCancelPromise(
+        cx, unwrappedTeeState->cancelPromise());
+    MOZ_ASSERT(unwrappedCancelPromise != nullptr);
+    if (!ResolveUnwrappedPromiseWithUndefined(cx, unwrappedCancelPromise)) {
+      return false;
+    }
+
     args.rval().setUndefined();
     return true;
   }
@@ -469,9 +475,11 @@ static bool TeeReaderReadHandler(JSContext* cx, unsigned argc, Value* vp) {
   return cancelPromise;
 }
 
-/**
- * Streams spec, 3.4.10. step 18:
- * Upon rejection of reader.[[closedPromise]] with reason r,
+/*
+ * https://streams.spec.whatwg.org/#readable-stream-tee
+ * ReadableStreamTee(stream, cloneForBranch2)
+ *
+ * Step 18: Upon rejection of reader.[[closedPromise]] with reason r,
  */
 static bool TeeReaderErroredHandler(JSContext* cx, unsigned argc,
                                     JS::Value* vp) {
@@ -482,22 +490,34 @@ static bool TeeReaderErroredHandler(JSContext* cx, unsigned argc,
 
   Rooted<ReadableStreamDefaultController*> unwrappedBranchController(cx);
 
-  // Step 18.a.i: Perform
+  // Step 18.1: Perform
   //               ! ReadableStreamDefaultControllerError(
-  //                   branch1.[[readableStreamController]], r).
+  //                   branch1.[[controller]], r).
   unwrappedBranchController = teeState->branch1();
   if (!ReadableStreamControllerError(cx, unwrappedBranchController, reason)) {
     return false;
   }
 
-  // Step a.ii: Perform
+  // Step 18.2: Perform
   //            ! ReadableStreamDefaultControllerError(
-  //                branch2.[[readableStreamController]], r).
+  //                branch2.[[controller]], r).
   unwrappedBranchController = teeState->branch2();
   if (!ReadableStreamControllerError(cx, unwrappedBranchController, reason)) {
     return false;
   }
 
+  // Step 18.3: If canceled1 is false or canceled2 is false,
+  //            resolve cancelPromise with undefined.
+  if (!teeState->canceled1() || !teeState->canceled2()) {
+    Rooted<PromiseObject*> unwrappedCancelPromise(cx,
+                                                  teeState->cancelPromise());
+    MOZ_ASSERT(unwrappedCancelPromise != nullptr);
+
+    if (!ResolveUnwrappedPromiseWithUndefined(cx, unwrappedCancelPromise)) {
+      return false;
+    }
+  }
+
   args.rval().setUndefined();
   return true;
 }