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@rbxts/expect > ExpectMessageBuilder > index

ExpectMessageBuilder.index() method​

Sets a value for the index placeholder.

Signature:

index(index?: number | string): this;

Parameters​

Parameter

Type

Description

index

number | string

(Optional)

Returns:

this

This instance, for chaining.

Remarks​

Usually, indexies are attached as metadata, but sometimes you might also want to show the index in your message.

That's where the index placeholder comes into play.

Example​

For example, lets say we were testing if two arrays are equal.

new ExpectMessageBuilder(
  `Expected the array ${place.actual.value} to ${place.not} equal ${place.expected.value}`
).failureSuffix(`, but the ${place.index}nth element ${place.reason}`);

We might use logic like so:

for(const [index, value] of ipairs(actual)) {
  if(expected[index] !== actual[index]) {
    return message.failWithReason("had a different value");
  }
}

Which would result in the following output:

Expected the array [1,2,3] to equal [1,2,4], but the 3nth element had a different value