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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 https://github.com/nodejs/help/issues/221 as the prehistory. PR-URL: https://github.com/nodejs/node/pull/7741 Reviewed-By: Anna Henningsen <anna@addaleax.net>
68 lines
2.0 KiB
JavaScript
68 lines
2.0 KiB
JavaScript
'use strict';
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const common = require('../common');
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const assert = require('assert');
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const fs = require('fs');
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const path = require('path');
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const rl = require('readline');
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const BOM = '\uFEFF';
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// Get the data using a non-stream way to compare with the streamed data.
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const modelData = fs.readFileSync(
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path.join(common.fixturesDir, 'file-to-read-without-bom.txt'), 'utf8'
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);
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const modelDataFirstCharacter = modelData[0];
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// Detect the number of forthcoming 'line' events for mustCall() 'expected' arg.
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const lineCount = modelData.match(/\n/g).length;
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// Ensure both without-bom and with-bom test files are textwise equal.
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assert.strictEqual(
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fs.readFileSync(
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path.join(common.fixturesDir, 'file-to-read-with-bom.txt'), 'utf8'
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),
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`${BOM}${modelData}`
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);
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// An unjustified BOM stripping with a non-BOM character unshifted to a stream.
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const inputWithoutBOM = fs.createReadStream(
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path.join(common.fixturesDir, 'file-to-read-without-bom.txt'), 'utf8'
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);
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inputWithoutBOM.once('readable', common.mustCall(() => {
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const maybeBOM = inputWithoutBOM.read(1);
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assert.strictEqual(maybeBOM, modelDataFirstCharacter);
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assert.notStrictEqual(maybeBOM, BOM);
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inputWithoutBOM.unshift(maybeBOM);
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let streamedData = '';
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rl.createInterface({
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input: inputWithoutBOM,
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}).on('line', common.mustCall((line) => {
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streamedData += `${line}\n`;
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}, lineCount)).on('close', common.mustCall(() => {
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assert.strictEqual(streamedData, modelData);
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}));
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}));
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// A justified BOM stripping.
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const inputWithBOM = fs.createReadStream(
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path.join(common.fixturesDir, 'file-to-read-with-bom.txt'), 'utf8'
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);
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inputWithBOM.once('readable', common.mustCall(() => {
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const maybeBOM = inputWithBOM.read(1);
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assert.strictEqual(maybeBOM, BOM);
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let streamedData = '';
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rl.createInterface({
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input: inputWithBOM,
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}).on('line', common.mustCall((line) => {
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streamedData += `${line}\n`;
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}, lineCount)).on('close', common.mustCall(() => {
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assert.strictEqual(streamedData, modelData);
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}));
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}));
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