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README.md

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+# express-reqest-mock
+
+Express middleware to mock requests with JSON and JS files.
+
+## Features
+
+- File based mocks using JSON and JS files.
+- Flexible configuration with [cosmiconfig](https://www.npmjs.com/package/cosmiconfig).
+- Supports preflight requests using [cors](https://www.npmjs.com/package/cors).
+- Uses express style path matching with [path-to-regexp](https://www.npmjs.com/package/path-to-regexp).
+
+## Installation
+
+```
+npm i express-request-mock
+```
+
+## Usage
+
+```
+const express = require("express");
+const mocker = require("express-request-mock");
+
+const app = express();
+
+// Add middleware as early as possible.
+app.use(mocker());
+
+// Setup routes etc.
+```
+
+## Setup
+
+It uses [cosmiconfig](https://www.npmjs.com/package/cosmiconfig) and thus supports any of the following:
+
+- `ermock` property in `package.json`
+- `.ermockrc` file in JSON or YAML format
+- `.ermockrc.json` file
+- `.ermockrc.yaml`, `.ermockrc.yml`, or `.ermockrc.js` file
+- `ermock.config.js` file exporting a JS object
+
+Furthemore it also accepts a configuration object when setting up in express, eg.:
+
+```
+app.use(mocker({
+    root: "/api/",
+    dir: "my-mock-reposnses",
+    delay: 500,
+    table: { ... }
+}));
+```
+
+the complete configuration will consist of default values, file based configuration (cosmiconfig) and object based configuration merged in the mentioned order.  
+This makes it possible to dynamically overwrite properties, e.g. the `root` prefix upon application load.
+
+## Configuration
+
+The configuration object accepts the following properties:
+
+| Property      | Type             | Default value | Description                                                             |
+| ------------- | ---------------- | ------------- | ----------------------------------------------------------------------- |
+| `root`        | string           | `""`          | Path prefix, e.g. `"/api"`                                              |
+| `dir`         | string           | `""`          | Folder name where mock files can be found, e.g. `"mocks"`               |
+| `table`       | string or object | `{}`          | Filename or object with url path as key and filename as key, see below. |
+| `delay`       | number           | `0`           | Add delay to reponses in milliseconds.                                  |
+| `corsOptions` | object           | `{}`          | Options object to use with [cors](https://www.npmjs.com/package/cors).  |
+
+## Table configuration
+
+The `table` accepts either a filename (relative to application root) or an object with the table configuration.  
+If you supply a filename it will be loaded automatically, e.g. `mocks/table.json` or `mock-table.json`.
+
+The object must:
+
+- have `url path` as **key**, starting with forward slash and excluding the `root` prefix.
+- have `filename` as **value**, either a `.json` file or `.js` file returning a method.
+
+The path matching is done with [path-to-regexp](https://www.npmjs.com/package/path-to-regexp) using **default options**.
+
+Example of table configuration:
+
+```
+// mock-table.json
+{
+    "/myservice/users": "users.json",
+    "/myservice/user/:id": "user.js
+}
+
+// users.json
+{
+    "users": [
+        1,
+        2
+    ]
+}
+
+// user.js
+module.exports = function (props) {
+    const { id } = props;
+
+    if (id === 1) {
+        return {
+            id,
+            name: "Arnold S.",
+            email: "[email protected]",
+            username: "T800",
+            permissions: ["ALL"]
+        };
+    } else {
+        return {
+            id,
+            name: "Connor, Sarah",
+            email: "",
+            username: "donttrustthemachines",
+            permissions: ["RESTRICTED"]
+        }
+    }
+
+}
+```
+
+When a method is returned from the mock file, it is executed with the match object containing named keys and indexed values from the path matched. See the following example:
+
+```
+// table config
+{
+    "/service/subscription/:id([^/\\?]+)(\\?.*)?": "mockfile.js"
+}
+
+// req url:
+//  "/service/subscription/123?userinfo=true"
+
+// mockfile.js
+module.exports = function (props) {
+    // props = { '0': '?userinfo=true', id: '123' }
+}
+```
+
+For detailed configuration of the url path, see the [path-to-regexp readme](https://github.com/pillarjs/path-to-regexp#readme).
+
+## License
+
+MIT