Add writer implementation and tests

Author: Walker

lib/util.js

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+'use strict';
+
+const path = require('path');
+const { promisify } = require('util');
+const fs = require('fs');
+const readFile = promisify(fs.readFile);
+const { hasher } = require('asset-pipe-common');
+const readPkgUp = require('read-pkg-up');
+const postcss = require('postcss');
+const atImport = require('postcss-import');
+
+module.exports.identifyCssModule = function identifyCssModule (filePath) {
+    return readPkgUp({
+        normalize: false,
+        cwd: path.dirname(filePath),
+    }).then(result => {
+        const { name, version } = result.pkg;
+        const ref = filePath.replace(path.dirname(result.path), name);
+
+        return {
+            id: hasher(`${name}|${version}|${ref}`),
+            name,
+            version,
+            file: ref,
+        };
+    });
+};
+
+module.exports.bundleCssModule = function bundleCssModule (filePath) {
+    return readFile(filePath, 'utf8').then(css =>
+        postcss()
+            .use(atImport())
+            .process(css, {
+                from: filePath,
+            })
+            .then(({ css }) => css)
+    );
+};

lib/writer.js

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+'use strict';
+
+const { Readable } = require('stream');
+const { identifyCssModule, bundleCssModule } = require('./util');
+const { existsSync } = require('fs');
+const assert = require('assert');
+
+module.exports = class Writer extends Readable {
+    constructor (files = []) {
+        assert(Array.isArray(files), `Expected 'files' to be of type 'Array', instead got '${typeof files}'`);
+        for (const file of files) {
+            assert(typeof file === 'string', `Expected 'file' (${file}) to be of type 'string', instead got '${typeof file}'`);
+            assert(existsSync(file), `Expected 'file' (${file}) to exist on file system but it did not`);
+        }
+
+        super({ objectMode: true });
+        this.files = files;
+    }
+
+    _read () {
+        const file = this.files.shift();
+        if (!file) {
+            this.push(null);
+            return;
+        }
+        Promise.all([bundleCssModule(file), identifyCssModule(file)])
+            .then(([css, meta]) => {
+                meta.content = css;
+                this.push(meta);
+            })
+            .catch(err => {
+                process.nextTick(() => this.emit('error', err));
+            });
+    }
+};

test/test-assets/my-module-1/main.css

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+/* my-module-1/main.css */

test/test-assets/my-module-1/package.json

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+{
+    "name": "my-module-1",
+    "version": "1.0.1"
+}

test/test-assets/my-module-2/css/main.css

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+/* my-module-2/main.css */

test/test-assets/my-module-2/package.json

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+{
+    "name": "my-module-2",
+    "version": "1.0.1"
+}

test/test-assets/my-module-3/css/dep.css

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+/* my-module-3/dep.css */

test/test-assets/my-module-3/css/main.css

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+/* my-module-3/main.css */
+
+@import url('./dep.css');
+@import url('dep/main.css');

test/test-assets/my-module-3/package.json

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+{
+    "name": "my-module-3",
+    "version": "1.0.1"
+}

test/writer.test.js

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+'use strict';
+
+const path = require('path');
+const { hasher } = require('asset-pipe-common');
+const { identifyCssModule, bundleCssModule } = require('../lib/util.js');
+const Writer = require('..');
+
+test('identifyCssModule(filePath)', async () => {
+    const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
+    const fileRef = 'my-module-1/main.css';
+
+    const result = await identifyCssModule(filePath);
+
+    const identifier = {
+        id: hasher(`my-module-1|1.0.1|${fileRef}`),
+        name: 'my-module-1',
+        version: '1.0.1',
+        file: fileRef
+    };
+    expect(result).toEqual(identifier);
+});
+
+test('identifyCssModule(filePath) css in nested directory', async () => {
+    const filePath = path.join(__dirname, 'test-assets/my-module-2/css/main.css');
+    const fileRef = 'my-module-2/css/main.css';
+
+    const result = await identifyCssModule(filePath);
+
+    const identifier = {
+        id: hasher(`my-module-2|1.0.1|${fileRef}`),
+        name: 'my-module-2',
+        version: '1.0.1',
+        file: fileRef
+    };
+    expect(result).toEqual(identifier);
+});
+
+test('bundleCssModule(filePath)', async () => {
+    const filePath = path.join(__dirname, 'test-assets/my-module-3/css/main.css');
+
+    const result = await bundleCssModule(filePath);
+
+    expect(result).toMatch('my-module-3/main.css');
+    expect(result).toMatch('my-module-3/dep.css');
+    expect(result).toMatch('dep/main.css');
+});
+
+test('new Writer([filePath])', () => {
+    const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
+    const fileRef = 'my-module-1/main.css';
+
+    const writer = new Writer([filePath]);
+    const items = [];
+
+    writer.on('data', item => {
+        items.push(item);
+    });
+
+    writer.on('end', () => {
+        const result1 = items[0];
+        const result2 = items[1];
+
+        expect(result1.id).toBe(hasher(`my-module-1|1.0.1|${fileRef}`));
+        expect(result2).toBeFalsy();
+    });
+});
+
+test('Writer processes @import statements', () => {
+    const filePath = path.join(__dirname, 'test-assets/my-module-3/css/main.css');
+    const fileRef = 'my-module-3/css/main.css';
+
+    const writer = new Writer([filePath]);
+    const items = [];
+
+    writer.on('data', item => {
+        items.push(item);
+    });
+
+    writer.on('end', () => {
+        const result1 = items[0];
+        const result2 = items[1];
+
+        expect(result1.id).toBe(hasher(`my-module-3|1.0.1|${fileRef}`));
+        expect(result1.content).toMatch('my-module-3/main.css');
+        expect(result1.content).toMatch('my-module-3/dep.css');
+        expect(result1.content).toMatch('dep/main.css');
+        expect(result2).toBeFalsy();
+    });
+});
+
+test('new Writer([filePath1, filePath2]) ensures correct order', () => {
+    const filePath1 = path.join(__dirname, 'test-assets/my-module-1/main.css');
+    const fileRef1 = 'my-module-1/main.css';
+    const filePath2 = path.join(__dirname, 'test-assets/my-module-2/css/main.css');
+    const fileRef2 = 'my-module-2/css/main.css';
+
+    const writer = new Writer([filePath1, filePath2]);
+    const items = [];
+
+    writer.on('data', item => {
+        items.push(item);
+    });
+
+    writer.on('end', () => {
+        const result1 = items[0];
+        const result2 = items[1];
+        const result3 = items[2];
+
+        expect(result1.id).toBe(hasher(`my-module-1|1.0.1|${fileRef1}`));
+        expect(result2.id).toBe(hasher(`my-module-2|1.0.1|${fileRef2}`));
+        expect(result3).toBeFalsy();
+    });
+});
+
+test('new Writer([filePath]) ensures filePath[] is an array', () => {
+    const filePath = null;
+
+    const result = () => new Writer(filePath);
+
+    expect(result).toThrow();
+});
+
+test('new Writer([filePath]) ensures filePath[] is an array of strings', () => {
+    const filePath = null;
+
+    const result = () => new Writer([filePath]);
+
+    expect(result).toThrow();
+});
+
+test('new Writer([filePath]) ensures valid filePaths provided', () => {
+    const filePath = 'fake.css';
+
+    const result = () => new Writer([filePath]);
+
+    expect(result).toThrow();
+});