Commit d40873d
test: ensure stream preprocessing order
Sometimes it is necessary to preprocess some initial bit
of a stream data before giving the entire stream
to the main processing function. Sometimes this bit should be extracted
from the stream before the main processing; sometimes it should be
returned to the stream. This test checks an order of stream
modes, methods and events for a possible preprocessing algorithm.
Stream BOM stripping is selected as a use case.
See nodejs/help#221 as the prehistory.
PR-URL: #7741
Reviewed-By: Anna Henningsen <anna@addaleax.net>1 parent 0e1f098 commit d40873d
3 files changed
Lines changed: 73 additions & 0 deletions
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| Original file line number | Diff line number | Diff line change | |
|---|---|---|---|
@@ -0,0 +1,3 @@ | |||
| 1 | + abc | ||
| 2 | + def | ||
| 3 | + ghi | ||
| Original file line number | Diff line number | Diff line change | |
|---|---|---|---|
@@ -0,0 +1,3 @@ | |||
| 1 | + abc | ||
| 2 | + def | ||
| 3 | + ghi | ||
| Original file line number | Diff line number | Diff line change | |
|---|---|---|---|
@@ -0,0 +1,67 @@ | |||
| 1 | + 'use strict'; | ||
| 2 | + const common = require('../common'); | ||
| 3 | + const assert = require('assert'); | ||
| 4 | + | ||
| 5 | + const fs = require('fs'); | ||
| 6 | + const path = require('path'); | ||
| 7 | + const rl = require('readline'); | ||
| 8 | + | ||
| 9 | + const BOM = '\uFEFF'; | ||
| 10 | + | ||
| 11 | + // Get the data using a non-stream way to compare with the streamed data. | ||
| 12 | + const modelData = fs.readFileSync( | ||
| 13 | + path.join(common.fixturesDir, 'file-to-read-without-bom.txt'), 'utf8' | ||
| 14 | + ); | ||
| 15 | + const modelDataFirstCharacter = modelData[0]; | ||
| 16 | + | ||
| 17 | + // Detect the number of forthcoming 'line' events for mustCall() 'expected' arg. | ||
| 18 | + const lineCount = modelData.match(/\n/g).length; | ||
| 19 | + | ||
| 20 | + // Ensure both without-bom and with-bom test files are textwise equal. | ||
| 21 | + assert.strictEqual( | ||
| 22 | + fs.readFileSync( | ||
| 23 | + path.join(common.fixturesDir, 'file-to-read-with-bom.txt'), 'utf8' | ||
| 24 | + ), | ||
| 25 | + `${BOM}${modelData}` | ||
| 26 | + ); | ||
| 27 | + | ||
| 28 | + // An unjustified BOM stripping with a non-BOM character unshifted to a stream. | ||
| 29 | + const inputWithoutBOM = fs.createReadStream( | ||
| 30 | + path.join(common.fixturesDir, 'file-to-read-without-bom.txt'), 'utf8' | ||
| 31 | + ); | ||
| 32 | + | ||
| 33 | + inputWithoutBOM.once('readable', common.mustCall(() => { | ||
| 34 | + const maybeBOM = inputWithoutBOM.read(1); | ||
| 35 | + assert.strictEqual(maybeBOM, modelDataFirstCharacter); | ||
| 36 | + assert.notStrictEqual(maybeBOM, BOM); | ||
| 37 | + | ||
| 38 | + inputWithoutBOM.unshift(maybeBOM); | ||
| 39 | + | ||
| 40 | + let streamedData = ''; | ||
| 41 | + rl.createInterface({ | ||
| 42 | + input: inputWithoutBOM, | ||
| 43 | + }).on('line', common.mustCall((line) => { | ||
| 44 | + streamedData += `${line}\n`; | ||
| 45 | + }, lineCount)).on('close', common.mustCall(() => { | ||
| 46 | + assert.strictEqual(streamedData, modelData); | ||
| 47 | + })); | ||
| 48 | + })); | ||
| 49 | + | ||
| 50 | + // A justified BOM stripping. | ||
| 51 | + const inputWithBOM = fs.createReadStream( | ||
| 52 | + path.join(common.fixturesDir, 'file-to-read-with-bom.txt'), 'utf8' | ||
| 53 | + ); | ||
| 54 | + | ||
| 55 | + inputWithBOM.once('readable', common.mustCall(() => { | ||
| 56 | + const maybeBOM = inputWithBOM.read(1); | ||
| 57 | + assert.strictEqual(maybeBOM, BOM); | ||
| 58 | + | ||
| 59 | + let streamedData = ''; | ||
| 60 | + rl.createInterface({ | ||
| 61 | + input: inputWithBOM, | ||
| 62 | + }).on('line', common.mustCall((line) => { | ||
| 63 | + streamedData += `${line}\n`; | ||
| 64 | + }, lineCount)).on('close', common.mustCall(() => { | ||
| 65 | + assert.strictEqual(streamedData, modelData); | ||
| 66 | + })); | ||
| 67 | + })); | ||
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