Merge pull request #14 from Lojdquist/master

Add Decoder.buffer

Author: MarcCoquand

package-lock.json

@@ -1,5 +1,5 @@
 {
-  "version": "6.1.1",
+  "version": "6.1.2",
   "license": "MIT",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",
@@ -42,6 +42,7 @@
   "module": "dist/decoders.esm.js",
   "devDependencies": {
     "@types/jest": "^25.2.1",
+    "@types/node": "^15.12.2",
     "@typescript-eslint/eslint-plugin": "^2.13.0",
     "@typescript-eslint/parser": "^2.13.0",
     "coveralls": "^3.0.9",

package.json

@@ -322,7 +322,7 @@ export class Decoder<T> {
   );
 
   /**
-   * A decoder that accepts undefined.
+   * A decoder that accepts null.
    *
    * Example:
    * ```
@@ -336,6 +336,22 @@ export class Decoder<T> {
       ? Result.ok(data)
       : Result.fail(makeSingleError('Not null', data))
   );
+  /**
+   * A decoder that accepts a Buffer.
+   *
+   * Example:
+   * ```
+   * Decoder.null.run(undefined) // FAIL
+   * Decoder.null.run(5) // FAIL
+   * Decoder.null.run(Buffer.from('Hello world')) // OK
+   * Decoder.null.run(<Buffer 68 65 6c 6c 6f>) // OK
+   *```
+   */
+  public static buffer: Decoder<Buffer> = new Decoder((data) =>
+    Buffer.isBuffer(data)
+      ? Result.ok(data)
+      : Result.fail(makeSingleError('Not Buffer', data))
+  );
 
   /**
    * Decodes a string.

src/index.ts

@@ -246,6 +246,24 @@ describe('Undefined decoder', () => {
   });
 });
 
+describe('Buffer decoder', () => {
+  it('decodes Buffer', () => {
+    const data = Buffer.from('hello');
+    const result = Decoder.buffer.run(data);
+    expect(result).toEqual({ type: 'OK', value: data });
+  });
+
+  it('does not decode invalid data', () => {
+    fc.assert(
+      fc.property(fc.anything(), (anything: any) => {
+        fc.pre(!Buffer.isBuffer(anything));
+        const res = Decoder.buffer.run(anything);
+        expect(res).toHaveProperty('type', 'FAIL');
+      })
+    );
+  });
+});
+
 describe('Methods', () => {
   it('map', () => {
     const setDecoder = Decoder.array(Decoder.number).map((arr) => new Set(arr));

test/decoder.test.ts

@@ -1127,6 +1127,11 @@
   resolved "https://registry.yarnpkg.com/@types/node/-/node-14.0.5.tgz#3d03acd3b3414cf67faf999aed11682ed121f22b"
   integrity sha512-90hiq6/VqtQgX8Sp0EzeIsv3r+ellbGj4URKj5j30tLlZvRUpnAe9YbYnjl3pJM93GyXU0tghHhvXHq+5rnCKA==
 
+"@types/node@^15.12.2":
+  version "15.12.2"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-15.12.2.tgz#1f2b42c4be7156ff4a6f914b2fb03d05fa84e38d"
+  integrity sha512-zjQ69G564OCIWIOHSXyQEEDpdpGl+G348RAKY0XXy9Z5kU9Vzv1GMNnkar/ZJ8dzXB3COzD9Mo9NtRZ4xfgUww==
+
 "@types/parse-json@^4.0.0":
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/@types/parse-json/-/parse-json-4.0.0.tgz#2f8bb441434d163b35fb8ffdccd7138927ffb8c0"