1.0.2

Update the getLayers method to take in an array of the layer filenames you expect to be in the gerber archive. This will allow the package to be used with gerbers that output different filenames for each layer then EAGLE.

.eslintrc.json

@@ -1,11 +0,0 @@
-{
-    "extends": ["airbnb-base", "prettier", "plugin:node/recommended"],
-    "env": {
-        "node": true
-    },
-    "plugins": ["prettier"],
-    "rules": {
-        "prettier/prettier": "error",
-        "no-console": "off"
-    }
-}

.gitignore

@@ -75,22 +75,12 @@ typings/
 # parcel-bundler cache (https://parceljs.org/)
 .cache
 
-# Next.js build output
-.next
-
-# Nuxt.js build / generate output
-.nuxt
-dist
-
 # Gatsby files
 .cache/
 # Comment in the public line in if your project uses Gatsby and *not* Next.js
 # https://nextjs.org/blog/next-9-1#public-directory-support
 # public
 
-# vuepress build output
-.vuepress/dist
-
 # Serverless directories
 .serverless/
 
@@ -106,4 +96,5 @@ dist
 .DS_Store
 gerber/
 hello.txt
-test/tmp/*
+test/tmp/*
+test/archiveTest

README.md

@@ -5,30 +5,91 @@
 **This is still being developed and isn't ready for production!**
 Only tested with gerbers generated by EAGLE.
 
-Requires node version 10 or higher.
+node version 20 or higher recommended.
 
 ## Usage
 
+### Save a PNG file
+
 ```
-const fileProc = require('@nplayfair/npe_gerber');
+const { ImageGenerator } = require('@nplayfair/npe_gerber');
 
 const folderConfig = {
     tmpDir: path.join(__dirname, 'tmp'),
     imgDir: path.join(__dirname, 'img')
 }
 
-const config = {
+const imageConfig = {
     resizeWidth: 600,
     density: 1000,
     compLevel: 1
 }
 
-fileProc.config(folderConfig);
+const layerNames = [
+  'CAMOutputs/DrillFiles/drills.xln',
+  'CAMOutputs/GerberFiles/copper_top.gbr',
+  'CAMOutputs/GerberFiles/silkscreen_top.gbr',
+  'CAMOutputs/GerberFiles/soldermask_top.gbr',
+  'CAMOutputs/GerberFiles/solderpaste_top.gbr',
+  'CAMOutputs/GerberFiles/profile.gbr',
+];
 
-let gerberArchive = '/path/to/gerber.zip';
+const gerberArchive = '/path/to/gerber.zip';
 
-fileProc.gerberToImage(gerberArchive, config, folderConfig.tmpDir, folderConfig.imgDir)
+const fileProc = new ImageGenerator(folderConfig, imageConfig, layerNames);
+
+fileProc.gerberToImage(gerberArchive)
       .then(filename => {
         console.log(`Generated image ${filename}`);
       })
-```
+```
+
+### Return a PNG stream
+
+```
+const { ImageGenerator } = require('@nplayfair/npe_gerber');
+
+const folderConfig = {
+    tmpDir: path.join(__dirname, 'tmp'),
+    imgDir: path.join(__dirname, 'img')
+}
+
+const imageConfig = {
+    resizeWidth: 600,
+    density: 1000,
+    compLevel: 1
+}
+
+const layerNames = [
+  'CAMOutputs/DrillFiles/drills.xln',
+  'CAMOutputs/GerberFiles/copper_top.gbr',
+  'CAMOutputs/GerberFiles/silkscreen_top.gbr',
+  'CAMOutputs/GerberFiles/soldermask_top.gbr',
+  'CAMOutputs/GerberFiles/solderpaste_top.gbr',
+  'CAMOutputs/GerberFiles/profile.gbr',
+];
+
+const gerberArchive = '/path/to/gerber.zip';
+
+const fileProc = new ImageGenerator(folderConfig, imageConfig, layerNames);
+
+fileProc.gerberToStream(gerberArchive)
+      .then(stream => {
+        // Do something with the stream
+      })
+```
+
+## Layer Names
+
+The constructor must be passed an array of filenames that correspond to the layers in the gerber archives you expect to be uploaded. The example above shows which names are used by EAGLE but other applications may use different filenames.
+
+## Image Processing Configuratation
+
+Several values need to be set in the image configuration object. An SVG vector is first created as an intermediate step before being converted to a PNG. These correspond to the parameters passed to [sharp](https://sharp.pixelplumbing.com/) for
+resizing the intermediary SVG and output PNG file. These settings are:
+
+- `resizeWidth`: Width in pixels of the output image.
+- `density`: DPI to create the SVG with. Low values will result in a poor quality output image.
+- `compLevel`: PNG compression level.
+
+More information about these settings can be found in the [sharp](https://sharp.pixelplumbing.com/) documentation.

dist/index.js

@@ -0,0 +1,198 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.ImageGenerator = void 0;
+//Modules
+// const AdmZip = require('adm-zip');
+const adm_zip_1 = __importDefault(require("adm-zip"));
+const fs_extra_1 = require("fs-extra");
+const path_1 = __importDefault(require("path"));
+const pcb_stackup_1 = __importDefault(require("pcb-stackup"));
+const sharp_1 = __importDefault(require("sharp"));
+const node_stream_1 = require("node:stream");
+const node_fs_1 = require("node:fs");
+//Class definition
+class ImageGenerator {
+    constructor(folderConfig, imgConfig, layerNames) {
+        this.folderConfig = folderConfig;
+        this.imgConfig = imgConfig;
+        this.layerNames = layerNames;
+        //Ensure folders exist
+        if (!(0, node_fs_1.existsSync)(folderConfig.tmpDir))
+            throw new Error('Temp dir does not exist');
+        if (!(0, node_fs_1.existsSync)(folderConfig.imgDir))
+            throw new Error('Image dir does not exist');
+        //Check folder permissions
+        (0, node_fs_1.accessSync)(folderConfig.tmpDir, node_fs_1.constants.R_OK | node_fs_1.constants.W_OK);
+        (0, node_fs_1.accessSync)(folderConfig.imgDir, node_fs_1.constants.R_OK | node_fs_1.constants.W_OK);
+    }
+    /**
+     * Extracts the passed in zip file
+  
+     */
+    extractArchive(fileName, tmpDir) {
+        // Check archive exists
+        if (!(0, node_fs_1.existsSync)(fileName)) {
+            throw Error('Archive does not exist.');
+        }
+        //Check temp folder exists
+        if (!(0, node_fs_1.existsSync)(tmpDir)) {
+            throw Error('Temporary folder does not exist.');
+        }
+        const zip = new adm_zip_1.default(fileName);
+        zip.extractAllTo(path_1.default.join(tmpDir, 'archive'));
+        return zip.getEntries().length;
+    }
+    //Test archive
+    testArchive(fileName, tmpDir) {
+        // Check archive exists
+        try {
+            if (!(0, node_fs_1.existsSync)(fileName)) {
+                throw Error('Archive does not exist.');
+            }
+            if (!(0, node_fs_1.existsSync)(tmpDir)) {
+                throw Error('Temporary folder does not exist.');
+            }
+        }
+        catch (e) {
+            console.error(e);
+        }
+        const zip = new adm_zip_1.default(fileName);
+        return zip.getEntries().length;
+    }
+    //Layer promise
+    getLayers(dir, layerNames) {
+        //Check correct number of layers and folder exists
+        layerNames.forEach((layerName) => {
+            if (!(0, node_fs_1.existsSync)(path_1.default.join(dir, layerName))) {
+                throw `Missing layer: ${layerName}`;
+            }
+        });
+        if (!(0, node_fs_1.existsSync)(dir)) {
+            throw new Error('Folder not there');
+        }
+        //Return layer promise
+        const layersPromise = new Promise(function (resolve, reject) {
+            const layers = layerNames.map((layerName) => ({
+                filename: layerName,
+                gerber: (0, node_fs_1.createReadStream)(path_1.default.join(dir, layerName)),
+            }));
+            if (layers.length === layerNames.length) {
+                resolve(layers);
+            }
+            else {
+                reject('Invalid layer count');
+            }
+        });
+        return layersPromise;
+    }
+    //Clean up the archive folder in the specified directory
+    static cleanupFiles(dir) {
+        try {
+            const folder = path_1.default.join(dir, 'archive');
+            (0, fs_extra_1.emptyDirSync)(folder);
+        }
+        catch (error) {
+            if (error instanceof Error) {
+                console.error(error.message);
+            }
+        }
+    }
+    //  * Take an archive containing gerber files, config object, temporary dir
+    //  * and output dir and create a PNG image from the gerber in the output dir
+    //  * @param {string} gerber Path to an archive file containing gerber
+    //  * @returns {Promise.<string>} Promise to return path to image
+    gerberToImage(gerber) {
+        // Create output dir if it doesn't exist
+        try {
+            (0, fs_extra_1.ensureDirSync)(this.folderConfig.imgDir);
+        }
+        catch (error) {
+            if (error instanceof Error) {
+                console.error(error.message);
+            }
+        }
+        // Check temp and output dirs exist
+        if (!(0, node_fs_1.existsSync)(gerber)) {
+            throw Error('Archive does not exist.');
+        }
+        if (!(0, node_fs_1.existsSync)(this.folderConfig.tmpDir)) {
+            throw Error('Temporary folder does not exist.');
+        }
+        if (!(0, node_fs_1.existsSync)(this.folderConfig.imgDir)) {
+            throw Error('Output folder does not exist.');
+        }
+        // Set filenames
+        //Use the filename of the gerber zip to determine the output png filename
+        const imageName = path_1.default.basename(gerber, '.zip');
+        const destFile = `${path_1.default.join(this.folderConfig.imgDir, imageName)}.png`;
+        return new Promise((resolve, reject) => {
+            if (!this.layerNames) {
+                throw new Error('You must supply an array of layer names.');
+            }
+            this.extractArchive(gerber, this.folderConfig.tmpDir);
+            this.getLayers(path_1.default.join(this.folderConfig.tmpDir, 'archive'), this.layerNames)
+                .then(pcb_stackup_1.default)
+                .then((stackup) => {
+                (0, sharp_1.default)(Buffer.from(stackup.top.svg), {
+                    density: this.imgConfig.density,
+                })
+                    .resize({ width: this.imgConfig.resizeWidth })
+                    .png({ compressionLevel: this.imgConfig.compLevel })
+                    .toFile(destFile);
+            })
+                .then(() => {
+                ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+                resolve(destFile);
+            })
+                .catch((e) => {
+                ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+                reject(new Error(e));
+            });
+        });
+    }
+    /**
+     * Take an archive containing gerber files and return a stream containing
+     * a PNG image from the gerber */
+    gerberToStream(gerber) {
+        // Check temp and output dirs exist
+        if (!(0, node_fs_1.existsSync)(gerber)) {
+            throw Error('Archive does not exist.');
+        }
+        if (!(0, node_fs_1.existsSync)(this.folderConfig.tmpDir)) {
+            throw Error('Temporary folder does not exist.');
+        }
+        if (!(0, node_fs_1.existsSync)(this.folderConfig.imgDir)) {
+            throw Error('Output folder does not exist.');
+        }
+        return new Promise((resolve, reject) => {
+            this.extractArchive(gerber, this.folderConfig.tmpDir);
+            if (!this.layerNames)
+                throw new Error('No layers provided');
+            this.getLayers(path_1.default.join(this.folderConfig.tmpDir, 'archive'), this.layerNames)
+                .then(pcb_stackup_1.default)
+                .then((stackup) => {
+                (0, sharp_1.default)(Buffer.from(stackup.top.svg), {
+                    density: this.imgConfig.density,
+                })
+                    .resize({ width: this.imgConfig.resizeWidth })
+                    .png({ compressionLevel: this.imgConfig.compLevel })
+                    .toBuffer()
+                    .then((buffer) => {
+                    ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+                    const stream = new node_stream_1.Readable();
+                    stream.push(buffer);
+                    stream.push(null);
+                    resolve(stream);
+                });
+            })
+                .catch((e) => {
+                ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+                reject(new Error(e));
+            });
+        });
+    }
+}
+exports.ImageGenerator = ImageGenerator;

eslint.config.mjs

@@ -0,0 +1,18 @@
+// @ts-check
+
+import eslint from '@eslint/js';
+import tseslint from 'typescript-eslint';
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  tseslint.configs.recommended,
+  {
+    ignores: [
+      'dist/**',
+      'test/**',
+      'node_modules/**',
+      'webpack.dev.js',
+      'webpack.prod.js',
+    ],
+  },
+);

index.js

@@ -1,154 +0,0 @@
-const AdmZip = require('adm-zip');
-const fs = require('fs-extra');
-const path = require('path');
-const pcbStackup = require('pcb-stackup');
-const sharp = require('sharp');
-
-// Filenames we need to extract from the archive
-const gerberFiles = [
-  'CAMOutputs/DrillFiles/drills.xln',
-  'CAMOutputs/GerberFiles/copper_top.gbr',
-  'CAMOutputs/GerberFiles/silkscreen_top.gbr',
-  'CAMOutputs/GerberFiles/soldermask_top.gbr',
-  'CAMOutputs/GerberFiles/solderpaste_top.gbr',
-  'CAMOutputs/GerberFiles/profile.gbr',
-];
-
-class ImageGenerator {
-  constructor(folderConfig, imgConfig) {
-    // this.folderConfig = folderConfig;
-    this.tmpDir = folderConfig.tmpDir;
-    this.imgDir = folderConfig.imgDir;
-    this.imgConfig = imgConfig;
-
-    // Ensure that the folders exist
-    try {
-      fs.ensureDirSync(this.tmpDir);
-      fs.ensureDirSync(this.imgDir);
-    } catch (error) {
-      throw new Error(error);
-    }
-  }
-
-  /**
-   * Extracts the passed in zip file
-   * @param {string} fileName Name of the file to be extracted
-   * @param {string} tmpDir Temporary directory to extract to
-   * @returns {Promise} Promise object represents number of files extracted
-   */
-  static extractArchive(fileName, tmpDir) {
-    // Check archive exists
-    try {
-      if (!fs.existsSync(fileName)) {
-        throw Error('Archive does not exist.');
-      }
-      if (!fs.existsSync(tmpDir)) {
-        throw Error('Temporary folder does not exist.');
-      }
-    } catch (e) {
-      throw new Error(e);
-    }
-
-    const zip = new AdmZip(fileName);
-    zip.extractAllTo(path.join(tmpDir, 'archive'));
-  }
-
-  /**
-   * Take in a directory of layer files and return an array of the layers files
-   * @param {string} dir Directory containing layer files
-   * @returns {Array} Array of paths to the layers files
-   */
-  static getLayers(dir) {
-    return new Promise((resolve, reject) => {
-      // Make sure the directory exists
-      if (!fs.existsSync(dir)) {
-        return reject(new Error('Layers folder does not exist.'));
-      }
-      // Check that the required layer files exist in source dir
-      let layersValid = true;
-      gerberFiles.forEach((layer) => {
-        if (!fs.existsSync(path.join(dir, layer))) layersValid = false;
-      });
-      if (!layersValid) return reject(new Error('Layer not found.'));
-      // Construct array of layers that match the supplied filenames array
-      const layers = gerberFiles.map((layerName) => ({
-        filename: layerName,
-        gerber: fs.createReadStream(path.join(dir, layerName)),
-      }));
-      return resolve(layers);
-    });
-  }
-
-  /**
-   * Clean up the archive folder in the specified directory
-   * @param {string} dir Path to a directory to clean up
-   */
-  static cleanupFiles(dir) {
-    try {
-      const folder = path.join(dir, 'archive');
-      fs.emptyDirSync(folder);
-    } catch (err) {
-      throw new Error(err);
-    }
-  }
-
-  /**
-   * Take an archive containing gerber files, config object, temporary dir
-   * and output dir and create a PNG image from the gerber in the output dir
-   * @param {string} gerber Path to an archive file containing gerber
-   * @returns {Promise.<string>} Promise to return path to image
-   */
-  gerberToImage(gerber) {
-    // Create output dir if it doesn't exist
-    try {
-      fs.ensureDirSync(this.imgDir, 0o644);
-    } catch (e) {
-      throw new Error(e);
-    }
-
-    // Check temp and output dirs exist
-    try {
-      if (!fs.existsSync(gerber)) {
-        throw Error('Archive does not exist.');
-      }
-      if (!fs.existsSync(this.tmpDir)) {
-        throw Error('Temporary folder does not exist.');
-      }
-      if (!fs.existsSync(this.imgDir)) {
-        throw Error('Output folder does not exist.');
-      }
-    } catch (e) {
-      throw new Error(e);
-    }
-
-    // Set filenames
-    const imageName = path.basename(gerber, '.zip');
-    const destFile = `${path.join(this.imgDir, imageName)}.png`;
-
-    return new Promise((resolve, reject) => {
-      ImageGenerator.extractArchive(gerber, this.tmpDir);
-      ImageGenerator.getLayers(path.join(this.tmpDir, 'archive'))
-        .then(pcbStackup)
-        .then((stackup) => {
-          sharp(Buffer.from(stackup.top.svg), {
-            density: this.imgConfig.density,
-          })
-            .resize({ width: this.imgConfig.resizeWidth })
-            .png({ compressionLevel: this.imgConfig.compLevel })
-            .toFile(destFile);
-        })
-        .then(() => {
-          ImageGenerator.cleanupFiles(this.tmpDir);
-          resolve(destFile);
-        })
-        .catch((e) => {
-          ImageGenerator.cleanupFiles(this.tmpDir);
-          reject(new Error(e));
-        });
-    });
-  }
-}
-
-module.exports = {
-  ImageGenerator,
-};

package.json

@@ -1,10 +1,14 @@
 {
   "name": "@nplayfair/npe_gerber",
-  "version": "0.1.1",
+  "version": "1.0.2",
   "description": "Create a PCB image from gerber files",
-  "main": "index.js",
+  "main": "dist/index.js",
+  "types": "types/npe_gerber.d.ts",
   "scripts": {
-    "test": "jest"
+    "build": "tsc --build",
+    "test": "NODE_ENV=test PORT=7788 jest",
+    "test:watch": "npm run test -- --watchAll",
+    "lint": "eslint ."
   },
   "repository": {
     "type": "git",
@@ -21,23 +25,48 @@
     "image",
     "gerber"
   ],
+  "jest": {
+    "verbose": true,
+    "modulePathIgnorePatterns": [
+      "<rootDir>/node_modules"
+    ],
+    "roots": [
+      "<rootDir>/test"
+    ],
+    "transform": {
+      "^.+\\.tsx?$": "ts-jest"
+    },
+    "testEnvironment": "node",
+    "testPathIgnorePatterns": [
+      "/node_modules"
+    ],
+    "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$",
+    "moduleFileExtensions": [
+      "ts",
+      "tsx",
+      "js",
+      "jsx",
+      "json",
+      "node"
+    ]
+  },
   "dependencies": {
-    "adm-zip": "^0.5.2",
-    "fs-extra": "^9.1.0",
-    "jszip": "^3.5.0",
-    "pcb-stackup": "^4.2.5",
-    "sharp": "^0.27.0"
+    "adm-zip": "^0.5.16",
+    "fs-extra": "^11.3.0",
+    "pcb-stackup": "^4.2.8",
+    "sharp": "^0.34.2"
   },
   "devDependencies": {
-    "eslint": "^7.19.0",
-    "eslint-config-airbnb-base": "^14.2.1",
-    "eslint-config-node": "^4.1.0",
-    "eslint-config-prettier": "^7.2.0",
-    "eslint-plugin-import": "^2.22.1",
-    "eslint-plugin-node": "^11.1.0",
-    "eslint-plugin-prettier": "^3.3.1",
-    "eslint-plugin-react": "^7.22.0",
-    "jest": "^26.6.3",
-    "prettier": "^2.2.1"
+    "@eslint/js": "^9.29.0",
+    "@types/adm-zip": "^0.5.7",
+    "@types/fs-extra": "^11.0.4",
+    "@types/jest": "^29.5.14",
+    "eslint": "^9.29.0",
+    "jest": "^30.0.0",
+    "prettier": "^3.5.3",
+    "ts-jest": "^29.4.0",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.8.3",
+    "typescript-eslint": "^8.34.0"
   }
 }

src/index.ts

@@ -0,0 +1,210 @@
+//Modules
+// const AdmZip = require('adm-zip');
+import AdmZip from 'adm-zip';
+import { emptyDirSync, ensureDirSync } from 'fs-extra';
+import path from 'path';
+import pcbStackup from 'pcb-stackup';
+import sharp from 'sharp';
+import { Readable } from 'node:stream';
+import { existsSync, accessSync, createReadStream, constants } from 'node:fs';
+
+//Class definition
+export class ImageGenerator implements ZipExtractor, LayerGenerator {
+  constructor(
+    public folderConfig: FolderConfig,
+    public imgConfig: ImageConfig,
+    public layerNames?: string[],
+  ) {
+    //Ensure folders exist
+    if (!existsSync(folderConfig.tmpDir))
+      throw new Error('Temp dir does not exist');
+
+    if (!existsSync(folderConfig.imgDir))
+      throw new Error('Image dir does not exist');
+
+    //Check folder permissions
+    accessSync(folderConfig.tmpDir, constants.R_OK | constants.W_OK);
+    accessSync(folderConfig.imgDir, constants.R_OK | constants.W_OK);
+  }
+
+  /**
+   * Extracts the passed in zip file
+
+   */
+  public extractArchive(fileName: string, tmpDir: string): number {
+    // Check archive exists
+    if (!existsSync(fileName)) {
+      throw Error('Archive does not exist.');
+    }
+    //Check temp folder exists
+    if (!existsSync(tmpDir)) {
+      throw Error('Temporary folder does not exist.');
+    }
+
+    const zip = new AdmZip(fileName);
+    zip.extractAllTo(path.join(tmpDir, 'archive'));
+
+    return zip.getEntries().length;
+  }
+
+  //Test archive
+  public testArchive(fileName: string, tmpDir: string): number {
+    // Check archive exists
+    try {
+      if (!existsSync(fileName)) {
+        throw Error('Archive does not exist.');
+      }
+      if (!existsSync(tmpDir)) {
+        throw Error('Temporary folder does not exist.');
+      }
+    } catch (e: unknown) {
+      console.error(e);
+    }
+    const zip = new AdmZip(fileName);
+    return zip.getEntries().length;
+  }
+
+  //Layer promise
+  public getLayers(dir: string, layerNames: string[]): Promise<Layers[]> {
+    //Check correct number of layers and folder exists
+    layerNames.forEach((layerName) => {
+      if (!existsSync(path.join(dir, layerName))) {
+        throw `Missing layer: ${layerName}`;
+      }
+    });
+    if (!existsSync(dir)) {
+      throw new Error('Folder not there');
+    }
+    //Return layer promise
+    const layersPromise = new Promise<Layers[]>(function (resolve, reject) {
+      const layers: Layers[] = layerNames.map((layerName: string) => ({
+        filename: layerName,
+        gerber: createReadStream(path.join(dir, layerName)),
+      }));
+      if (layers.length === layerNames.length) {
+        resolve(layers);
+      } else {
+        reject('Invalid layer count');
+      }
+    });
+    return layersPromise;
+  }
+
+  //Clean up the archive folder in the specified directory
+  public static cleanupFiles(dir: string): void {
+    try {
+      const folder = path.join(dir, 'archive');
+      emptyDirSync(folder);
+    } catch (error: unknown) {
+      if (error instanceof Error) {
+        console.error(error.message);
+      }
+    }
+  }
+
+  //  * Take an archive containing gerber files, config object, temporary dir
+  //  * and output dir and create a PNG image from the gerber in the output dir
+  //  * @param {string} gerber Path to an archive file containing gerber
+  //  * @returns {Promise.<string>} Promise to return path to image
+
+  public gerberToImage(gerber: string) {
+    // Create output dir if it doesn't exist
+    try {
+      ensureDirSync(this.folderConfig.imgDir);
+    } catch (error) {
+      if (error instanceof Error) {
+        console.error(error.message);
+      }
+    }
+
+    // Check temp and output dirs exist
+    if (!existsSync(gerber)) {
+      throw Error('Archive does not exist.');
+    }
+    if (!existsSync(this.folderConfig.tmpDir)) {
+      throw Error('Temporary folder does not exist.');
+    }
+    if (!existsSync(this.folderConfig.imgDir)) {
+      throw Error('Output folder does not exist.');
+    }
+
+    // Set filenames
+    //Use the filename of the gerber zip to determine the output png filename
+    const imageName = path.basename(gerber, '.zip');
+    const destFile = `${path.join(this.folderConfig.imgDir, imageName)}.png`;
+
+    return new Promise((resolve, reject) => {
+      if (!this.layerNames) {
+        throw new Error('You must supply an array of layer names.');
+      }
+      this.extractArchive(gerber, this.folderConfig.tmpDir);
+      this.getLayers(
+        path.join(this.folderConfig.tmpDir, 'archive'),
+        this.layerNames,
+      )
+        .then(pcbStackup)
+        .then((stackup) => {
+          sharp(Buffer.from(stackup.top.svg as ArrayLike<number>), {
+            density: this.imgConfig.density,
+          })
+            .resize({ width: this.imgConfig.resizeWidth })
+            .png({ compressionLevel: this.imgConfig.compLevel })
+            .toFile(destFile);
+        })
+        .then(() => {
+          ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+          resolve(destFile);
+        })
+        .catch((e) => {
+          ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+          reject(new Error(e));
+        });
+    });
+  }
+
+  /**
+   * Take an archive containing gerber files and return a stream containing
+   * a PNG image from the gerber */
+
+  gerberToStream(gerber: string) {
+    // Check temp and output dirs exist
+    if (!existsSync(gerber)) {
+      throw Error('Archive does not exist.');
+    }
+    if (!existsSync(this.folderConfig.tmpDir)) {
+      throw Error('Temporary folder does not exist.');
+    }
+    if (!existsSync(this.folderConfig.imgDir)) {
+      throw Error('Output folder does not exist.');
+    }
+
+    return new Promise((resolve, reject) => {
+      this.extractArchive(gerber, this.folderConfig.tmpDir);
+      if (!this.layerNames) throw new Error('No layers provided');
+      this.getLayers(
+        path.join(this.folderConfig.tmpDir, 'archive'),
+        this.layerNames,
+      )
+        .then(pcbStackup)
+        .then((stackup) => {
+          sharp(Buffer.from(stackup.top.svg as ArrayLike<number>), {
+            density: this.imgConfig.density,
+          })
+            .resize({ width: this.imgConfig.resizeWidth })
+            .png({ compressionLevel: this.imgConfig.compLevel })
+            .toBuffer()
+            .then((buffer) => {
+              ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+              const stream = new Readable();
+              stream.push(buffer);
+              stream.push(null);
+              resolve(stream);
+            });
+        })
+        .catch((e) => {
+          ImageGenerator.cleanupFiles(this.folderConfig.tmpDir);
+          reject(new Error(e));
+        });
+    });
+  }
+}

test/index.test.js

@@ -1,113 +0,0 @@
-/* eslint-disable */
-const path = require('path');
-const fs = require('fs-extra');
-const { ImageGenerator } = require('../index.js');
-require('../index.js');
-
-const testGerber = path.join(__dirname, 'Arduino-Pro-Mini.zip');
-const testLayers = path.join(__dirname, 'layers');
-const emptyFolder = path.join(__dirname, 'layers', 'Empty');
-const nonWritableDir = fs.ensureDirSync(path.join(folderConfig.tmpDir, 'no-write'), 0o400);
-const folderConfig = {
-  tmpDir: path.join(__dirname, 'tmp'),
-  imgDir: path.join(__dirname, 'tmp'),
-};
-const noTempConfig = {
-  tmpDir: emptyFolder,
-  imgDir: path.join(__dirname, 'tmp'),
-};
-const noImageConfig = {
-  tmpDir: path.join(__dirname, 'tmp'),
-  imgDir: emptyFolder,
-};
-const imgConfig = {
-  resizeWidth: 600,
-  density: 1000,
-  compLevel: 1,
-};
-
-const fileProc = new ImageGenerator(folderConfig, imgConfig);
-const fileProcNoTemp = new ImageGenerator(noTempConfig, imgConfig);
-const fileProcNoImage = new ImageGenerator(noImageConfig, imgConfig);
-
-/**************
- * Tests
- ***************/
-
-// getLayers
-test('Promise of an array of layers from a given folder', () => {
-  expect.assertions(1);
-  return ImageGenerator.getLayers(testLayers).then((data) => {
-    expect(data).toEqual(
-      expect.arrayContaining([
-        expect.objectContaining({
-          filename: expect.any(String),
-          gerber: expect.any(fs.ReadStream),
-        }),
-      ])
-    );
-  });
-});
-
-test('Non-existent folder should reject promise with error', () => {
-  expect.assertions(1);
-  return expect(ImageGenerator.getLayers('./invalid_folder')).rejects.toThrow(
-    new Error('Layers folder does not exist.')
-  );
-});
-
-test('Folder with incorrect number of layers should reject promise with error', () => {
-  expect.assertions(1);
-  return expect(ImageGenerator.getLayers(emptyFolder)).rejects.toThrow(
-    new Error('Layer not found.')
-  );
-});
-
-// extractArchive
-test('Non-existent archive should throw an error', () => {
-  expect(() =>
-    ImageGenerator.extractArchive('invalid.zip', folderConfig.tmpDir).toThrow(Error)
-  );
-});
-
-test('Temp dir not existing should throw an error', () => {
-  expect(() =>
-    ImageGenerator.extractArchive(testGerber, './invalid_dir').toThrow(Error)
-  );
-});
-
-test('Should extract archive and resolve with the number of files extracted', () => {
-  expect(() => ImageGenerator.extractArchive(testGerber, folderConfig.tmpDir).toBe(12));
-});
-
-// gerberToImage
-test('Temp dir not existing should throw an error', () => {
-  expect(() =>
-    fileProcNoTemp
-      .gerberToImage(testGerber)
-      .toThrow(new Error('Temporary folder does not exist.'))
-  );
-});
-
-test('Output dir not existing should throw an error', () => {
-  expect(() =>
-    fileProcNoImage
-      .gerberToImage(testGerber)
-      .toThrow(new Error('Output folder does not exist.'))
-  );
-});
-
-test('Invalid archive file should throw an error', () => {
-  expect(() =>
-    fileProc
-      .gerberToImage('invalid.zip')
-      .toThrow(new Error('Archive does not exist.'))
-  );
-});
-
-test('Gerber archive should resolve promise and return a filename of an image', () => {
-  expect.assertions(1);
-  return expect(
-    fileProc.gerberToImage(testGerber)
-  ).resolves.toEqual(expect.stringContaining('Arduino-Pro-Mini.png'));
-});

test/index.test.ts

@@ -0,0 +1,202 @@
+import path from 'path';
+import { readdirSync } from 'node:fs';
+import { emptyDirSync } from 'fs-extra';
+import { Readable } from 'node:stream';
+import { ImageGenerator } from '../src/index';
+import { tmpdir } from 'node:os';
+
+const testGerber = path.join(__dirname, 'Arduino-Pro-Mini.zip');
+const incompleteGerber = path.join(__dirname, 'incomplete.zip');
+const testLayers = path.join(__dirname, 'layers');
+const emptyFolder = path.join(__dirname, 'layers', 'Empty');
+const archiveTestFolder = path.join(__dirname, 'archiveTest');
+const folderConfig = {
+  tmpDir: path.join(__dirname, 'tmp'),
+  imgDir: path.join(__dirname, 'tmp'),
+};
+const noTempConfig = {
+  tmpDir: emptyFolder,
+  imgDir: path.join(__dirname, 'tmp'),
+};
+const tmpNotExist = {
+  tmpDir: path.join(__dirname, 'InvalidFolderName'),
+  imgDir: path.join(__dirname, 'tmp'),
+};
+const imgNotExist = {
+  tmpDir: path.join(__dirname, 'tmp'),
+  imgDir: path.join(__dirname, 'InvalidFolderName'),
+};
+const tmpBadPerms = {
+  tmpDir: path.join(__dirname, 'badPerms'),
+  imgDir: path.join(__dirname, 'tmp'),
+};
+const imgBadPerms = {
+  tmpDir: path.join(__dirname, 'tmp'),
+  imgDir: path.join(__dirname, 'badPerms'),
+};
+const noImageConfig = {
+  tmpDir: path.join(__dirname, 'tmp'),
+  imgDir: emptyFolder,
+};
+const imgConfig = {
+  resizeWidth: 600,
+  density: 1000,
+  compLevel: 1,
+};
+const layerNames = [
+  'CAMOutputs/DrillFiles/drills.xln',
+  'CAMOutputs/GerberFiles/copper_top.gbr',
+  'CAMOutputs/GerberFiles/silkscreen_top.gbr',
+  'CAMOutputs/GerberFiles/soldermask_top.gbr',
+  'CAMOutputs/GerberFiles/solderpaste_top.gbr',
+  'CAMOutputs/GerberFiles/profile.gbr',
+];
+
+const fileProc = new ImageGenerator(folderConfig, imgConfig, layerNames);
+
+/**************
+ * Tests
+ ***************/
+
+beforeAll(() => {
+  return emptyDirSync(folderConfig.tmpDir);
+});
+
+beforeEach(() => {
+  return emptyDirSync(emptyFolder);
+});
+
+// Test constructor
+describe('Creating an ImageGenerator object', () => {
+  const imgGen = new ImageGenerator(folderConfig, imgConfig);
+  test('should create a valid object when passed the correct files and configuration', () => {
+    expect(imgGen).toBeInstanceOf(ImageGenerator);
+  });
+  // Image processing configuration
+  test('image width should be 600', () => {
+    expect(imgGen.imgConfig.resizeWidth).toBe(600);
+  });
+  test('image density should be 1000', () => {
+    expect(imgGen.imgConfig.density).toBe(1000);
+  });
+  test('image compression level should be 1', () => {
+    expect(imgGen.imgConfig.compLevel).toBe(1);
+  });
+  test('folders should be the ones specified in the folder config parameter', () => {
+    expect(imgGen.folderConfig.tmpDir).toBe(path.join(__dirname, 'tmp'));
+    expect(imgGen.folderConfig.imgDir).toBe(path.join(__dirname, 'tmp'));
+  });
+  afterAll(() => {
+    return emptyDirSync(folderConfig.tmpDir);
+  });
+});
+
+// Testing folder config
+describe('Passing in', () => {
+  test('a non-existent tmp folder should throw error', () => {
+    expect(() => {
+      new ImageGenerator(tmpNotExist, imgConfig);
+    }).toThrow();
+  });
+  test('a tmp folder with invalid permissions should throw error', () => {
+    expect(() => {
+      new ImageGenerator(tmpBadPerms, imgConfig);
+    }).toThrow();
+  });
+  test('a non-existent img folder should throw error', () => {
+    expect(() => {
+      new ImageGenerator(imgNotExist, imgConfig);
+    }).toThrow();
+  });
+  test('an img folder with invalid permissions should throw error', () => {
+    expect(() => {
+      new ImageGenerator(imgBadPerms, imgConfig);
+    }).toThrow();
+  });
+});
+
+//Layer methods
+describe('Getting layers', () => {
+  const imgGen = new ImageGenerator(folderConfig, imgConfig);
+  test('should return a promise of array of layers', () => {
+    expect(imgGen.getLayers(testLayers, layerNames)).resolves.toBeInstanceOf(
+      Array,
+    );
+  });
+
+  test('should throw error if the layers folder is not valid', () => {
+    expect(() => {
+      imgGen.getLayers('some_invalid_folder', layerNames);
+    }).toThrow();
+  });
+
+  test('should throw error if incorrect number of layers supplied', () => {
+    expect(() => {
+      imgGen.getLayers(emptyFolder, layerNames);
+    }).toThrow();
+  });
+});
+
+//Archive methods
+describe('When extracting an archive', () => {
+  const imgGen = new ImageGenerator(folderConfig, imgConfig);
+  test('a non-existent archive should throw an error', () => {
+    expect(() =>
+      imgGen.extractArchive('invalid.zip', folderConfig.tmpDir),
+    ).toThrow();
+  });
+  test('if the temp dir does not exist it should throw an error', () => {
+    expect(() => imgGen.extractArchive(testGerber, 'some_invalid_dir')).toThrow(
+      Error,
+    );
+  });
+  test('it should load the archive and return the number of files extracted', () => {
+    expect(() => {
+      imgGen.testArchive(testGerber, archiveTestFolder);
+    }).not.toThrow();
+    expect(imgGen.testArchive(testGerber, archiveTestFolder)).toEqual(12);
+  });
+  test('it should extract archive and all files should be present', () => {
+    expect(imgGen.testArchive(testGerber, archiveTestFolder)).toEqual(12);
+    imgGen.extractArchive(testGerber, archiveTestFolder);
+    const dirents = readdirSync(archiveTestFolder, {
+      recursive: true,
+      withFileTypes: true,
+    });
+    const numOutputFiles = dirents.filter((dirent) => dirent.isFile());
+    expect(numOutputFiles).toHaveLength(12);
+  });
+  //clear archive
+  afterAll(() => {
+    return emptyDirSync(archiveTestFolder);
+  });
+});
+
+//Gerber methods
+describe('Converting a gerber to an image', () => {
+  beforeEach(() => {
+    return emptyDirSync(emptyFolder);
+  });
+  afterAll(() => {
+    return emptyDirSync(emptyFolder);
+  });
+
+  test('invalid archive file should throw an error', () => {
+    expect(() => fileProc.gerberToImage('invalid.zip')).toThrow();
+  });
+  // test('an archive with incomplete set of layers should throw an error', () => {
+  //   expect(() => fileProc.gerberToImage(incompleteGerber)).toThrow();
+  // });
+  test('gerber archive should resolve promise and return a filename of an image', () => {
+    expect.assertions(1);
+    return expect(fileProc.gerberToImage(testGerber)).resolves.toEqual(
+      expect.stringContaining('Arduino-Pro-Mini.png'),
+    );
+  });
+  test('Gerber archive should resolve promise and return a png stream', () => {
+    expect.assertions(1);
+    return expect(fileProc.gerberToStream(testGerber)).resolves.toBeInstanceOf(
+      Readable,
+    );
+  });
+});

tsconfig.json

@@ -0,0 +1,115 @@
+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig to read more about this file */
+
+    /* Projects */
+    // "incremental": true,                              /* Save .tsbuildinfo files to allow for incremental compilation of projects. */
+    // "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
+    // "tsBuildInfoFile": "./.tsbuildinfo",              /* Specify the path to .tsbuildinfo incremental compilation file. */
+    // "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects. */
+    // "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
+    // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */
+
+    /* Language and Environment */
+    "target": "es2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
+    // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
+    // "jsx": "preserve",                                /* Specify what JSX code is generated. */
+    // "libReplacement": true,                           /* Enable lib replacement. */
+    // "experimentalDecorators": true,                   /* Enable experimental support for legacy experimental decorators. */
+    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
+    // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'. */
+    // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
+    // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using 'jsx: react-jsx*'. */
+    // "reactNamespace": "",                             /* Specify the object invoked for 'createElement'. This only applies when targeting 'react' JSX emit. */
+    // "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
+    // "useDefineForClassFields": true,                  /* Emit ECMAScript-standard-compliant class fields. */
+    // "moduleDetection": "auto",                        /* Control what method is used to detect module-format JS files. */
+
+    /* Modules */
+    "module": "commonjs" /* Specify what module code is generated. */,
+    // "rootDir": "./",                                  /* Specify the root folder within your source files. */
+    // "moduleResolution": "node10",                     /* Specify how TypeScript looks up a file from a given module specifier. */
+    // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
+    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
+    // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
+    // "typeRoots": [],                                  /* Specify multiple folders that act like './node_modules/@types'. */
+    // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
+    // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
+    // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
+    // "rewriteRelativeImportExtensions": true,          /* Rewrite '.ts', '.tsx', '.mts', and '.cts' file extensions in relative import paths to their JavaScript equivalent in output files. */
+    // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
+    // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
+    // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    // "noUncheckedSideEffectImports": true,             /* Check side effect imports. */
+    // "resolveJsonModule": true,                        /* Enable importing .json files. */
+    // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
+    // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
+
+    /* JavaScript Support */
+    // "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
+    // "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
+    // "maxNodeModuleJsDepth": 1,                        /* Specify the maximum folder depth used for checking JavaScript files from 'node_modules'. Only applicable with 'allowJs'. */
+
+    /* Emit */
+    // "declaration": true,                              /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
+    // "declarationMap": true,                           /* Create sourcemaps for d.ts files. */
+    // "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
+    // "sourceMap": true,                                /* Create source map files for emitted JavaScript files. */
+    // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
+    // "noEmit": true,                                   /* Disable emitting files from a compilation. */
+    // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
+    "outDir": "./dist" /* Specify an output folder for all emitted files. */,
+    // "removeComments": true,                           /* Disable emitting comments. */
+    // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
+    // "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
+    // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
+    // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSources": true,                            /* Include source code in the sourcemaps inside the emitted JavaScript. */
+    // "emitBOM": true,                                  /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
+    // "newLine": "crlf",                                /* Set the newline character for emitting files. */
+    // "stripInternal": true,                            /* Disable emitting declarations that have '@internal' in their JSDoc comments. */
+    // "noEmitHelpers": true,                            /* Disable generating custom helper functions like '__extends' in compiled output. */
+    // "noEmitOnError": true,                            /* Disable emitting files if any type checking errors are reported. */
+    // "preserveConstEnums": true,                       /* Disable erasing 'const enum' declarations in generated code. */
+    // "declarationDir": "./",                           /* Specify the output directory for generated declaration files. */
+
+    /* Interop Constraints */
+    // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
+    // "verbatimModuleSyntax": true,                     /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
+    // "isolatedDeclarations": true,                     /* Require sufficient annotation on exports so other tools can trivially generate declaration files. */
+    // "erasableSyntaxOnly": true,                       /* Do not allow runtime constructs that are not part of ECMAScript. */
+    // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
+    "esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */,
+    // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
+    "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,
+
+    /* Type Checking */
+    "strict": true /* Enable all strict type-checking options. */,
+    // "noImplicitAny": true,                            /* Enable error reporting for expressions and declarations with an implied 'any' type. */
+    // "strictNullChecks": true,                         /* When type checking, take into account 'null' and 'undefined'. */
+    // "strictFunctionTypes": true,                      /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
+    // "strictBindCallApply": true,                      /* Check that the arguments for 'bind', 'call', and 'apply' methods match the original function. */
+    // "strictPropertyInitialization": true,             /* Check for class properties that are declared but not set in the constructor. */
+    // "strictBuiltinIteratorReturn": true,              /* Built-in iterators are instantiated with a 'TReturn' type of 'undefined' instead of 'any'. */
+    // "noImplicitThis": true,                           /* Enable error reporting when 'this' is given the type 'any'. */
+    // "useUnknownInCatchVariables": true,               /* Default catch clause variables as 'unknown' instead of 'any'. */
+    // "alwaysStrict": true,                             /* Ensure 'use strict' is always emitted. */
+    // "noUnusedLocals": true,                           /* Enable error reporting when local variables aren't read. */
+    // "noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read. */
+    // "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
+    // "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
+    // "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
+    // "noUncheckedIndexedAccess": true,                 /* Add 'undefined' to a type when accessed using an index. */
+    // "noImplicitOverride": true,                       /* Ensure overriding members in derived classes are marked with an override modifier. */
+    // "noPropertyAccessFromIndexSignature": true,       /* Enforces using indexed accessors for keys declared using an indexed type. */
+    // "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
+    // "allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */
+
+    /* Completeness */
+    // "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. */
+    "skipLibCheck": true /* Skip type checking all .d.ts files. */
+  },
+  "include": ["src/**/*", "types/npe_gerber.d.ts"],
+  "exclude": ["node_modules", "dist/**/*", "test/**/*"]
+}

types/npe_gerber.d.ts

@@ -0,0 +1,23 @@
+interface ImageConfig {
+  resizeWidth: number;
+  density: number;
+  compLevel: number;
+}
+
+interface FolderConfig {
+  tmpDir: string;
+  imgDir: string;
+}
+
+interface ZipExtractor {
+  extractArchive(fileName: string, tmpDir: string): number;
+}
+
+interface Layers {
+  filename: string;
+  gerber: ReadStream;
+}
+
+interface LayerGenerator {
+  getLayers(dir: string, layerNames: string[]): Promise<Layers[]>;
+}