Fix async test reporting and resolve async test262 failures by lahma · Pull Request #2359 · sebastienros/jint (original) (raw)

and others added 19 commits

March 24, 2026 22:08

Improve test262 runner to properly detect async test failures via $DONE/doneprintHandle.js markers, then fix the root causes surfaced:

• AsyncFromSyncIterator.Next(): forward value argument to sync iterator using cached [[NextMethod]] per spec (was passing Arguments.Empty)
• Await: remove extra microtask tick by eliminating unnecessary resultCapability and AddToEventLoop wrapper in promise reaction handlers
• yield* delegation: cache nextMethod once before loop per spec, and always Await inner iterator results (handles thenables, not just JsPromise)
• AsyncFromSyncIterator: wrap GetMethod/done/value access in try-catch to reject promise on error; reject with TypeError for non-object results

Remaining async failures excluded by category for incremental fixing.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Resume execution with Return/Throw completion types instead of bypassing the generator body, fixing three interconnected issue categories:

• AsyncGeneratorResumeNext: for Return completions on SuspendedYield, resume execution with _resumeCompletionType=Return instead of calling AsyncGeneratorAwaitReturn directly. This allows try/finally blocks to execute and yield* delegation to forward return to inner iterators.
• ContinueAsyncYieldDelegate: override _delegationResumeType with _resumeCompletionType when user called .throw()/.return() during yield* delegation, so the completion flows to inner iterator.
• AwaitAndYieldDelegation: capture delegationResumeType and propagate Return completion when inner iterator returns done=true, enabling proper cleanup through try/finally in the outer generator.

Resolves 132 additional test262 failures (190 total with prior commit). Remaining 244 failures excluded by category for incremental fixing.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Wrap IteratorComplete and IteratorValue calls in AwaitAndYieldDelegation's onFulfilled handler with try-catch to properly reject the promise when the result object's done or value getters throw. Previously, these exceptions would propagate uncaught, breaking the generator state.

Resolves 48 additional test262 failures (238 total across all commits).

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

• Close async iterators when mapfn throws, mapped value rejects, or CreateDataPropertyOrThrow fails (IfAbruptCloseAsyncIterator per spec)
• Fix onRejected handlers to pass args.At(0) instead of full args array
• Add RangeError check for array-like length > 2^32-1

Resolves 12 additional Array.fromAsync test262 failures (250 total).

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Clear _returnRequested for async generators (not just sync) before executing finally blocks in JintTryStatement. Without this, a yield inside finally would be treated as a return, overwriting the pending return value and preventing proper completion after finally.

This enables the PendingCompletionType/Value mechanism to correctly restore the original Return completion after the finally block yields and completes.

Resolves 8 additional test262 failures (258 total across all commits).

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Per spec, when an async generator returns, the return value must be Awaited via PromiseResolve to unwrap promise values:

• SuspendedStart + Return: use AsyncGeneratorAwaitReturn instead of directly resolving (unwraps promise return values)
• Completed + Return: same treatment
• ResumeExecution: when body returns with Return completion, await the value via AsyncGeneratorAwaitReturn before completing

This ensures .return(promise) unwraps the promise value, and .return(brokenPromise) properly rejects when PromiseResolve fails.

Resolves 6 additional test262 failures (264 total across all commits).

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

• AsyncFromSyncIterator throw: set closeOnRejection to true per spec
• yield* delegation: propagate IteratorValue errors to generator body as throw completions instead of rejecting the promise directly
• Async generator return at yield: try PromiseResolve at yield point so broken promise errors reach the body's try/catch
• AsyncGeneratorAwaitReturn: catch PromiseResolve failures and reject
• AsyncDisposableStack.disposeAsync: return rejected promise on invalid receiver instead of throwing synchronously
• Promise.any: set iteratorRecord.[[Done]] to true before propagating IteratorStep/IteratorValue errors to prevent unnecessary iterator close

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

• Destructuring: generalize yield/return handling to work with both sync and async generators via ISuspendable interface (was sync-only)
• For-await-of: save current iterator value when yield suspends inside destructuring, replay it on resume instead of re-calling next()
• For-await-of: preserve IsResuming flag when resuming from yield in destructuring so the yield expression can detect the resume
• AsyncGeneratorInstance: use undefined for normal completion value per spec (was incorrectly using the body's last expression value)

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

• ScriptFunction: skip DisposeResources for async functions (disposal must be deferred until the async body truly completes)
• AsyncBlockStart: call DisposeResources after body completes, before resolving/rejecting the async function's promise
• AsyncFunctionResume: same disposal at completion, skip when suspended
• Fixes using/await-using disposal timing in async functions: resources are no longer disposed while the function is suspended at an await
• Tick ordering and deferred-await-in-async-generator tests remain excluded (require full async await suspension architecture)

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

• Array.fromAsync: catch TypeErrorException and RangeErrorException (thrown by TypeConverter without Engine context) and reject the promise instead of letting them escape as synchronous throws
• Un-exclude expression-yield-newline (already passes)
• Un-exclude asyncitems-arraylike-length-accessor-throws (now passes)

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Previously, await inside async generator bodies fell through to the blocking UnwrapIfPromise path because JintAwaitExpression only checked for AsyncFunctionInstance (null for async generators). This caused deadlocks on deferred promises and wrong microtask tick ordering.

• AsyncGeneratorInstance: add _awaitSuspended, _resumeWithThrow, and _completedAwaits fields; update IsSuspended to check _awaitSuspended
• JintAwaitExpression: add async generator resume/cache/suspend paths with SuspendForAwaitInAsyncGenerator method using promise handlers that resume via AsyncGeneratorContinueForAwait
• ResumeExecution/ResumeAfterDelegation: detect _awaitSuspended and return early (await handler resumes later)
• AsyncGeneratorYield: clear _completedAwaits on yield
• All loop statements: clear _completedAwaits for async generators at iteration boundaries (matching async function pattern)

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

• ResumeExecution: call DisposeResources on the lexical environment before leaving the execution context when the body completes
• ResumeAfterDelegation: same disposal at completion
• Both catch blocks: dispose resources before rejecting
• Fixes using/await-using in async generators: resources are now properly disposed when the generator body completes

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

… and un-exclude passing tests

Array.fromAsync: don't await async iterator values when no mapfn (spec 3.j.ii.8), use ulong for length overflow check, wrap SetLength in try-catch to reject promise. Async generators: distinguish return; (no await) from return expr; (await per 13.10.1), cache PromiseResolve from yield return path to avoid double thenable "then" access. Un-exclude 14 previously over-excluded tests that were already passing.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

For-await-of: add PromiseResolve call per spec Await step 1 (13.7.5.13) to make Promise.constructor lookups observable. Fixes 6 ticks-with tests.

AsyncGeneratorYield: use PromiseResolve instead of CreateResolvedPromise to avoid creating an extra thenable job when yielding Promise values. This fixes microtask interleaving between for-await-of and Promise.then.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Per spec Dispose step 3.a, even when method is undefined (null/undefined resource), async-dispose must Await(result). This introduces a microtask tick that suspends the async function.

DisposeCapability signals NeedsAsyncTick when it encounters an async-dispose resource with no method. JintBlockStatement detects this after block exit and creates a resolved promise to suspend the async function, ensuring statements after the block run in a new microtask.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Per spec AsyncGeneratorUnwrapYieldResumption step 2, the resumption value must be Awaited before yield* delegation continues. Additionally, when GetMethod("return") returns undefined, spec step 25.iii.1 requires a second Await on the received value.

Split the yield* Return branch into async phases: Phase A: Await(resumptionValue) — makes "then" getter observable before "return" Phase B: GetMethod("return") lookup, then second Await if return is undefined

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Per spec IncrementModuleAsyncEvaluationCount, the [[ModuleAsyncEvaluationCount]] is a field of the Agent Record, not local to each Evaluate() call. When dynamic import() triggers a new Evaluate() call, the counter must persist to maintain correct relative ordering between pending async modules.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

…sues

• Remove dead Agent.ModuleAsyncEvaluationCount (duplicate of Engine field)
• Extract ExecutionContext.ClearCompletedAwaitsIfNotResuming() replacing 4 copy-pasted blocks
• Extract AsyncGeneratorInstance.AbortDelegation()/ClearDelegationIterator() replacing ~13 inline blocks
• Fix bare catch to catch(Exception) in ArrayConstructor.AsyncIteratorClose
• Use CommonProperties.Return instead of string literals in JintYieldExpression
• Revert CreateResolvedPromise to private (no external callers)
• Clear _completedAwaits on generator completion to release references

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

…c generator yield

Two fixes:

1. import.meta now uses OrdinaryObjectCreate(null) per spec instead of Object.Construct(), which gave it Object.prototype. This caused import(import.meta) to reject with a string instead of TypeError.

2. JintMemberExpression.GetValue fast path now checks IsSuspended() after evaluating the object expression. Without this, an await suspension inside a chained expression like (await x).value.x would fall through to the slow path, re-evaluating the await and preventing the statement list _index from being saved correctly. This caused side-effectful statements (like generator .next() calls) to re-execute on every async function resume, corrupting generator state.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Two fixes to enable all 60 previously excluded Atomics.waitAsync tests:

1. Agent worker event loop draining: worker threads now drain the event loop after engine.Execute() until agent.leaving() is called, allowing async continuations from await Atomics.waitAsync() to be processed.

2. For-of loop environment corruption on async resume: when a for-of body contains let declarations and await, the saved execution context captured a block-scoped environment. On resume, BodyEvaluation captured this as oldEnv instead of the function scope, corrupting the environment chain for subsequent iterations. Fixed by saving/restoring oldEnv in ForOfSuspendData.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

lahma deleted the analyze-async branch

March 24, 2026 21:39

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