Add matcher to check for charset.

README.md

@@ -343,6 +343,16 @@ expect(req).to.be.html;
 expect(req).to.be.text;
 ```
 
+### .charset
+
+
+
+Assert that a `Response` or `Request` object has a given charset.
+
+```js
+expect(req).to.have.charset('utf-8');
+```
+
 ### .redirect
 
 

lib/http.js

@@ -21,6 +21,7 @@ module.exports = function (chai, _) {
   var qs = require('qs');
   var url = require('url');
   var Cookie = require('cookiejar');
+  var charset = require("charset");
 
   /*!
    * Aliases.
@@ -239,6 +240,40 @@ module.exports = function (chai, _) {
     .keys(contentTypes)
     .forEach(checkContentType);
 
+  /**
+   * ### .charset
+   *
+   * Assert that a `Response` or `Request` object has a given charset.
+   *
+   * ```js
+   * expect(req).to.have.charset('utf-8');
+   * ```
+   *
+   * @name charset
+   * @api public
+   */
+
+  Assertion.addMethod('charset', function (value) {
+    value = value.toLowerCase();
+
+    var headers = this._obj.headers;
+    var cs = charset(headers);
+
+    /*
+     * Fix charset() treating "utf8" as a special case
+     * See https://github.com/node-modules/charset/issues/12
+     */
+    if (cs === "utf8") {
+      cs = "utf-8";
+    }
+
+    this.assert(
+      cs != null && value === cs
+      , 'expected content type to have ' + value + ' charset'
+      , 'expected content type to not have ' + value + ' charset'
+    )
+  });
+
   /**
    * ### .redirect
    *

package.json

@@ -52,6 +52,7 @@
   "dependencies": {
     "@types/chai": "4",
     "@types/superagent": "^3.8.3",
+    "charset": "^1.0.1",
     "cookiejar": "^2.1.1",
     "is-ip": "^2.0.0",
     "methods": "^1.1.2",

test/http.js

@@ -403,4 +403,33 @@ describe('assertions', function () {
     }).should.throw('expected cookie \'name2\' to have value \'value\' but got \'value2\'');
 
   });
+
+  describe('#charset', function () {
+    it("should match charset in content type", function() {
+      var req = { headers: { 'content-type': [ 'text/plain; charset=utf-8' ] } };
+      req.should.to.have.charset("utf-8");
+
+      (function () {
+        req.should.not.have.charset("utf-8");
+      }).should.throw('expected content type to not have utf-8 charset');
+    });
+
+    it("should handle no content type", function() {
+      var req = { headers: {} };
+      req.should.not.have.charset("utf-8");
+
+      (function () {
+        req.should.to.have.charset("utf-8");
+      }).should.throw('expected content type to have utf-8 charset');
+    });
+
+    it("should handle no charset in content type", function() {
+      var req = { headers: { 'content-type': [ 'text/plain' ] } };
+      req.should.not.have.charset("utf-8");
+
+      (function () {
+        req.should.to.have.charset("utf-8");
+      }).should.throw('expected content type to have utf-8 charset');
+    });
+  });
 });

types/index.d.ts

@@ -35,6 +35,8 @@ declare global {
 
             header(key: string, value?: string | RegExp): Assertion;
 
+            charset(charset: string): Assertion;
+
             headers: Assertion;
             json: Assertion;
             text: Assertion;