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Files whose name ends in `_.js` are not themselves valid Test262 tests
and should not be interpreted as such by test runners.
---
Because the tests in this patch concern declaration *instantiation*,
care has been taken to avoid asserting binding values following
evaluation. Because a given module's dependencies are evaluated prior to
the module itself, this is only observable in modules which import their
own bindings.
A separate patch dedicated to the evaluation of module code asserts the
behavior of bindings following evaluation.
---
For tests that concern the creation of a module namespace object, this
patch relies on the semantics of the `in` operator. The `in` operator
uses the [[HasProperty]] internal method and avoids testing unrelated
semantics concerning binding resolution. Those semantics should be
explicitly asserted with a separate set of tests dedicated to that
purpose.
---
One test case which is notably missing is error resulting from a cycle
due to an `import` declaration (under the current file naming scheme,
such a test might be named `instn-named-err-circular.js`). Due to the
recursive nature of ModuleDeclarationInstantiation, it is not
technically possible for a circular request to be found in step 12.c.i.
Cycles rely on at least 2 `export` declarations, and because these are
resolved *before* imports, any cycle would trigger failure prior to step
12.c.
---
One aspect of *module* resolution that makes ordering observable is the
fact that resolution can fail in two distinct ways (i.e. with a
SyntaxError or with a ReferenceError). This patch includes tests that
leverage this detail in order to assert that modules are resolved in the
correct sequence.
However, from the perspective of the ECMA-262 specification, the
ordering of *export* (e.g. binding) resolution is not observable. This
is due to restrictions on the grammar, where each export is independent.
When *export* resolution fails, it does so with instances of SyntaxError
alone, precluding the above strategy.
So while ModuleDeclarationInstantiation resolves the exports of the
module's dependencies in the following order:
1. "Indirect" exports, e.g.
- `export { x } from './y.js';`
- `export { x as z } from './y.js';`
- `import { x } from './y.js'; export { x };`
2. "Star" imports
- `import * as ns from './y.js';`
3. "Named" (my word) imports
- `import x from './y.js';`
- `import { x } from './y.js';`
- `import { x as z } from './y.js';`
Intentional failures cannot be used to discern resolution ordering.
43 lines
1.3 KiB
JavaScript
43 lines
1.3 KiB
JavaScript
// Copyright (C) 2016 the V8 project authors. All rights reserved.
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// This code is governed by the BSD license found in the LICENSE file.
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/*---
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description: >
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An ImportClause without an ImportsList contributes to the list of requested
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modules
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esid: sec-moduledeclarationinstantiation
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info: |
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[...]
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8. For each String required that is an element of
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module.[[RequestedModules]] do,
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a. NOTE: Before instantiating a module, all of the modules it requested
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must be available. An implementation may perform this test at any
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time prior to this point.
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b. Let requiredModule be ? HostResolveImportedModule(module, required).
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c. Perform ? requiredModule.ModuleDeclarationInstantiation().
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15.2.2.5 Static Semantics: ModuleRequests
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ImportDeclaration : import ImportClause FromClause;
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1. Return ModuleRequests of FromClause.
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15.2.3 Exports
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Syntax
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ImportClause :
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ImportedDefaultBinding
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NameSpaceImport
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NamedImports
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ImportedDefaultBinding , NameSpaceImport
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ImportedDefaultBinding , NamedImports
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NamedImports :
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{ }
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{ ImportsList }
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{ ImportsList , }
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negative: ReferenceError
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flags: [module]
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---*/
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import {} from './instn-resolve-empty-import_.js';
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