Add test case where IteratorBindingInitialization throws when evaluating initializer#4926
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Add test case where IteratorBindingInitialization throws when evaluating initializer#4926
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Hello.
This PR adds a test case where IteratorBindingInitialization of BindingElement : BindingPattern Initializer? throws in step 3.a and step 3.b.
Step 3.a
initializer-evaluation-throws-unaryexpressionIn IteratorBindingInitialization of BindingElement : BindingPattern Initializer? step 3.a evaluation of Initializer is performed.
In this particular test file, Evaluation of UnaryExpression : '+' UnaryExpression is performed.
In Evaluation of UnaryExpression : '+' UnaryExpression step 1, Evaluation of IdentifierReference : Identifier is performed. And as a result, ResolveBinding is called.
ResolveBinding calls GetIdentifierReference. Since the identifier
xis not declared in the current environment record, GetIdentifierReference traverses the environment chain until it reaches the global environment (where env is null). It returns a Reference Record where the [[Base]] property is set tounresolvable(as per GetIdentifierReference step 1.a).Back in Evaluation of UnaryExpression : + UnaryExpression step 2, GetValue(expr) is called.
In GetValue step 2, IsUnresolvableReference(V) returns true because V.[[Base]] is
unresolvable. Consequently, GetValue throws a ReferenceError.Step 3.b
initializer-evaluation-throws-identifierIn IteratorBindingInitialization of BindingElement : BindingPattern Initializer? step 3.a, evaluation of Initializer is performed.
In this particular test file, Evaluation of IdentifierReference : Identifier is performed.
In Evaluation of IdentifierReference : Identifier step 1, ResolveBinding is called.
ResolveBinding calls GetIdentifierReference. Since the identifier x is not declared in the current environment record, GetIdentifierReference traverses the environment chain until it reaches the global environment (where env is null). It returns a Reference Record where the [[Base]] property is set to
unresolvable(as per GetIdentifierReference step 1.a).Back in IteratorBindingInitialization of BindingElement : BindingPattern Initializer? step 3.b, GetValue(expr) is called with the unresolvable Reference Record obtained from the previous step.
In GetValue step 2, IsUnresolvableReference(V) returns true because V.[[Base]] is
unresolvable. Consequently, GetValue throws a ReferenceError.