when piped through

<array> [when] piped through <array|Stream> <assertion?>

Write an array of Buffers or strings to a transform stream or a sequence of transform streams, then delegate to another assertion using the last stream as the subject.

Use this assertion when a certain behavior is only achievable when the input is chunked in a certain way.

It's intended to be used with the to yield output satisfying assertion:

return expect(

['foo', 'bar'],

'when piped through',

require('zlib').Gzip(),

'to yield output satisfying',

'to have length',

);

Example with multiple transform streams:

return expect(

[Buffer.from([0x01, 0x02]), Buffer.from([0x03, 0x04])],

'when piped through',

[require('zlib').Gzip(), require('zlib').Gunzip()],

'to yield output satisfying',

Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05])

);

expected [ Buffer.from([0x01, 0x02]), Buffer.from([0x03, 0x04]) ]

when piped through [ Gzip, Gunzip ] to yield output satisfying Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05])

expected Gunzip

to yield output satisfying Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05])

expected Buffer.from([0x01, 0x02, 0x03, 0x04])

to equal Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05])

01 02 03 04 │....│

01 02 03 04 05 │.....│

If you don't provide an assertion to delegate to, the target stream will be provided as the fulfillment value of the promise:

var zlib = require('zlib');

return expect('foobar', 'piped through', zlib.Gzip()).then(function (

targetStream

) {

return expect(targetStream, 'to be a', zlib.Gzip);

});