Test that resetting [[ModuleAsyncEvaluationCount]] is unobserbable

Author: nicolo-ribaudo

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset-a_FIXTURE.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+import { logs } from "./unobservable-global-async-evaluation-count-reset-setup_FIXTURE.js";
+import "./unobservable-global-async-evaluation-count-reset-b_FIXTURE.js";
+logs.push("A");

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset-b_FIXTURE.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+import { pB, pB_start } from "./unobservable-global-async-evaluation-count-reset-setup_FIXTURE.js";
+pB_start.resolve();
+await pB.promise;

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset-c_FIXTURE.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+await 1;

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset-d_FIXTURE.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+import { logs } from "./unobservable-global-async-evaluation-count-reset-setup_FIXTURE.js";
+import "./unobservable-global-async-evaluation-count-reset-e_FIXTURE.js";
+import "./unobservable-global-async-evaluation-count-reset-b_FIXTURE.js";
+logs.push("D");

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset-e_FIXTURE.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+import { pE_start } from "./unobservable-global-async-evaluation-count-reset-setup_FIXTURE.js";
+pE_start.resolve();

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset-setup_FIXTURE.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+export const logs = [];
+export const pB = Promise.withResolvers();
+export const pB_start = Promise.withResolvers();
+export const pE_start = Promise.withResolvers();

test/language/module-code/top-level-await/unobservable-global-async-evaluation-count-reset.js

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+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  An implementation may unobservably reset [[ModuleAsyncEvaluationCount]] to 0
+  whenever there are no pending modules.
+info: |
+  IncrementModuleAsyncEvaluationCount ( )
+    1. Let AR be the Agent Record of the surrounding agent.
+    2. Let count be AR.[[ModuleAsyncEvaluationCount]].
+    3. Set AR.[[ModuleAsyncEvaluationCount]] to count + 1.
+    4. Return count.
+
+    NOTE: This value is only used to keep track of the relative evaluation order
+    between pending modules. An implementation may unobservably reset
+    [[ModuleAsyncEvaluationCount]] to 0 whenever there are no pending modules.
+
+  InnerModuleEvaluation ( module, stack, index )
+    ...
+    12. If module.[[PendingAsyncDependencies]] > 0 or module.[[HasTLA]] is true, then
+      a. Assert: module.[[AsyncEvaluationOrder]] is unset.
+      b. Set module.[[AsyncEvaluationOrder]] to IncrementModuleAsyncEvaluationCount().
+      ...
+
+  AsyncModuleExecutionFulfilled ( module )
+    ...
+     9. Perform GatherAvailableAncestors(module, execList).
+    10. ...
+    11. Let sortedExecList be a List whose elements are the elements of execList, sorted by their [[AsyncEvaluationOrder]] field in ascending order.
+    12. For each Cyclic Module Record m of sortedExecList, do
+      a. If m.[[Status]] is evaluated, then
+        i. Assert: m.[[EvaluationError]] is not empty.
+      b. Else if m.[[HasTLA]] is true, then
+        i. Perform ExecuteAsyncModule(m).
+      c. Else,
+        i. Let result be m.ExecuteModule().
+        ...
+
+  Module graph (the order of dependencies in each module is important, and it's left-to-right):
+        ┌─────┐    ┌─────┐    ┌─────┐
+        │  A  │    │  C  │    │  D  │
+        └─────┘    └─────┘    └─────┘
+           │                   │   │
+           │                   ▼   │
+           │              ┌─────┐  │
+           │              │  E  │  │
+           │              └─────┘  │
+           │    ┌──────────────────┘
+           ▼    ▼
+         ┌───────┐
+         │   B   │
+         └───────┘
+
+  Where B and C have top-level await. The test orchestrates the evaluation order such that:
+  - Import A first
+  - Once B starts evaluating, import C and immediately resolve its top-level await
+  - Once C finishes evaluating, import D
+  - Once E is evaluated, resolve B's await
+
+esid: sec-IncrementModuleAsyncEvaluationCount
+flags: [module, async]
+features: [top-level-await, dynamic-import, promise-with-resolvers]
+includes: [compareArray.js]
+---*/
+
+import { logs, pB, pB_start, pE_start } from "./unobservable-global-async-evaluation-count-reset-setup_FIXTURE.js";
+
+const pA = import("./unobservable-global-async-evaluation-count-reset-a_FIXTURE.js");
+let pD;
+
+pB_start.promise.then(() => {
+  return import("./unobservable-global-async-evaluation-count-reset-c_FIXTURE.js");
+}).then(() => {
+  pD = import("./unobservable-global-async-evaluation-count-reset-d_FIXTURE.js");
+  return pE_start.promise;
+}).then(() => {
+  pB.resolve();
+  return Promise.all([pA, pD]);
+}).then(() => {
+  assert.compareArray(logs, ["A", "D"], "A should evaluate before D");
+}).then($DONE, $DONE);