Remove multi-type support for a/an assertion

lib/chai/core/assertions.js

@@ -125,7 +125,7 @@ module.exports = function (chai, _) {
   });
 
   /**
-   * ### .a(types)
+   * ### .a(type)
    *
    * The `a` and `an` assertions are aliases that can be
    * used either as language chains or to assert a value's
@@ -146,35 +146,23 @@ module.exports = function (chai, _) {
    *     // language chain
    *     expect(foo).to.be.an.instanceof(Foo);
    *
-   * When an array of strings is passed as argument of the assertion, the
-   * value's type must be one of them.
-   *
-   *     expect(myScalar).to.be.a(['string', 'number', 'boolean']);
-   *     expect([]).to.not.be.a(['string', 'number', 'boolean']);
-   *
    * @name a
    * @alias an
-   * @param {String|Array} types
+   * @param {String} type
    * @param {String} message _optional_
    * @api public
    */
 
-  function an (types, msg) {
+  function an (type, msg) {
     if (msg) flag(this, 'message', msg);
-    if (_.type(types) === 'string') types = [types];
-    types = types.map(function (t) { return t.toLowerCase(); });
-    var obj = flag(this, 'object');
-
-    var str = types.map(function (t, index) {
-      var art = ~[ 'a', 'e', 'i', 'o', 'u' ].indexOf(t.charAt(0)) ? 'an' : 'a';
-      var or = types.length > 1 && index === types.length - 1 ? 'or ' : '';
-      return or + art + ' ' + t;
-    }).join(', ');
+    type = type.toLowerCase();
+    var obj = flag(this, 'object')
+      , article = ~[ 'a', 'e', 'i', 'o', 'u' ].indexOf(type.charAt(0)) ? 'an ' : 'a ';
 
     this.assert(
-        types.some(function (expected) { return _.type(obj) === expected; })
-      , 'expected #{this} to be ' + str
-      , 'expected #{this} not to be ' + str
+        type === _.type(obj)
+      , 'expected #{this} to be ' + article + type
+      , 'expected #{this} not to be ' + article + type
     );
   }
 

test/expect.js

@@ -119,28 +119,6 @@ describe('expect', function () {
     err(function(){
       expect(5).to.not.be.a('number', 'blah');
     }, "blah: expected 5 not to be a number");
-
-    expect('foo').to.be.a(['string', 'number', 'boolean']);
-    expect(42).to.be.a(['string', 'number', 'boolean']);
-    expect(true).to.be.a(['string', 'number', 'boolean']);
-
-    err(function(){
-      expect([]).to.be.a(['string', 'number', 'boolean']);
-    }, 'expected [] to be a string, a number, or a boolean');
-
-    expect([]).to.not.be.a(['string', 'number', 'boolean']);
-
-    err(function(){
-      expect('foo').to.not.be.a(['string', 'number', 'boolean']);
-    }, 'expected \'foo\' not to be a string, a number, or a boolean');
-
-    err(function(){
-      expect(42).to.not.be.a(['string', 'number', 'boolean']);
-    }, 'expected 42 not to be a string, a number, or a boolean');
-
-    err(function(){
-      expect(true).to.not.be.a(['string', 'number', 'boolean']);
-    }, 'expected true not to be a string, a number, or a boolean');
   });
 
   it('instanceof', function(){

test/should.js

@@ -151,28 +151,6 @@ describe('should', function() {
     err(function(){
       (5).should.not.be.a('number');
     }, "expected 5 not to be a number");
-
-    'foo'.should.be.a(['string', 'number', 'boolean']);
-    (42).should.be.a(['string', 'number', 'boolean']);
-    (true).should.be.a(['string', 'number', 'boolean']);
-
-    err(function(){
-      [].should.be.a(['string', 'number', 'boolean']);
-    }, 'expected [] to be a string, a number, or a boolean');
-
-    [].should.not.be.a(['string', 'number', 'boolean']);
-
-    err(function(){
-      'foo'.should.not.be.a(['string', 'number', 'boolean']);
-    }, 'expected \'foo\' not to be a string, a number, or a boolean');
-
-    err(function(){
-      (42).should.not.be.a(['string', 'number', 'boolean']);
-    }, 'expected 42 not to be a string, a number, or a boolean');
-
-    err(function(){
-      (true).should.not.be.a(['string', 'number', 'boolean']);
-    }, 'expected true not to be a string, a number, or a boolean');
   });
 
   it('instanceof', function(){