diff --git a/test/assert.js b/test/assert.js
index 912aa18f..db2e1025 100644
--- a/test/assert.js
+++ b/test/assert.js
@@ -139,6 +139,20 @@ describe('assert', function () {
     assert.typeOf('test', 'string');
     assert.typeOf(true, 'boolean');
     assert.typeOf(5, 'number');
+    
+    assert.typeOf(() => {}, 'function');
+    assert.typeOf(function() {}, 'function');
+    assert.typeOf(async function() {}, 'asyncfunction');
+    assert.typeOf(function*() {}, 'generatorfunction');
+    assert.typeOf(async function*() {}, 'asyncgeneratorfunction');
+    
+    err(function () {
+      assert.typeOf(5, 'function', 'blah');
+    }, "blah: expected 5 to be a function");
+    
+    err(function () {
+      assert.typeOf(function() {}, 'asyncfunction', 'blah');
+    }, "blah: expected [Function] to be an asyncfunction");
 
     if (typeof Symbol === 'function') {
       assert.typeOf(Symbol(), 'symbol');
@@ -151,10 +165,20 @@ describe('assert', function () {
 
   it('notTypeOf', function () {
     assert.notTypeOf('test', 'number');
+    
+    assert.notTypeOf(() => {}, 'string');
+    assert.notTypeOf(function() {}, 'string');
+    assert.notTypeOf(async function() {}, 'string');
+    assert.notTypeOf(function*() {}, 'string');
+    assert.notTypeOf(async function*() {}, 'string');
 
     err(function () {
       assert.notTypeOf(5, 'number', 'blah');
     }, "blah: expected 5 not to be a number");
+    
+    err(function () {
+      assert.notTypeOf(() => {}, 'function', 'blah');
+    }, "blah: expected [Function] not to be a function");
   });
 
   it('instanceOf', function() {
@@ -547,6 +571,16 @@ describe('assert', function () {
       assert.isCallable({}, 'blah');
     }, "blah: expected {} to be a callable function");
   });
+  
+  it('isNotCallable', function() {
+    assert.isNotCallable(false);
+    assert.isNotCallable(10);
+    assert.isNotCallable('string');
+
+    err(function () {
+      assert.isNotCallable(function() {}, 'blah');
+    }, "blah: expected [Function] not to be a callable function");
+  });
 
   it('isNotFunction', function () {
     assert.isNotFunction(5);
diff --git a/test/expect.js b/test/expect.js
index e1d54a4b..d5247655 100644
--- a/test/expect.js
+++ b/test/expect.js
@@ -391,6 +391,29 @@ describe('expect', function () {
     expect(function*() {}).to.be.callable;
     expect(async function*() {}).to.be.callable;
     
+    expect('foobar').to.not.be.callable;
+    
+    err(function(){
+      expect('foobar', 'blah').to.be.callable;
+    }, "blah: expected 'foobar' to be a callable function");
+    
+    err(function(){
+      expect(function() {}, 'blah').to.not.be.callable;
+    }, "blah: expected [Function] not to be a callable function");
+  });
+    
+  it('function', function() {
+    expect(function() {}).to.be.a('function');
+    expect(async function() {}).to.be.a('function');
+    expect(function*() {}).to.be.a('function');
+    expect(async function*() {}).to.be.a('function');
+    
+    expect('foobar').to.not.be.a('function');
+    
+    err(function(){
+      expect('foobar').to.be.a('function', 'blah');
+    }, "blah: expected 'foobar' to be a function");
+
     err(function(){
       expect(function() {}).to.not.be.a('function', 'blah');
     }, "blah: expected [Function] not to be a function");
@@ -404,6 +427,10 @@ describe('expect', function () {
     expect(async function() {}).to.be.a('AsyncFunction');
     expect(async function*() {}).to.be.a('AsyncFunction');
 
+    err(function(){
+      expect('foobar').to.be.a('asyncfunction', 'blah');
+    }, "blah: expected 'foobar' to be an asyncfunction");
+
     err(function(){
       expect(async function() {}).to.not.be.a('asyncfunction', 'blah');
     }, "blah: expected [AsyncFunction] not to be an asyncfunction");
@@ -417,6 +444,10 @@ describe('expect', function () {
     expect(function*() {}).to.be.a('generatorFunction');
     expect(async function*() {}).to.be.a('generatorFunction');
     
+    err(function(){
+      expect('foobar').to.be.a('generatorfunction', 'blah');
+    }, "blah: expected 'foobar' to be a generatorfunction");
+    
     err(function(){
       expect(function*() {}).to.not.be.a('generatorfunction', 'blah');
     }, "blah: expected [GeneratorFunction] not to be a generatorfunction");
@@ -429,6 +460,10 @@ describe('expect', function () {
   it('asyncGeneratorFunction', function() {
     expect(async function*() {}).to.be.a('asyncGeneratorFunction');
     
+    err(function(){
+      expect(async function() {}, 'blah').to.be.a('asyncgeneratorfunction');
+    }, "blah: expected [AsyncFunction] to be an asyncgeneratorfunction");
+    
     err(function(){
       expect(async function*() {}, 'blah').to.not.be.a('asyncgeneratorfunction');
     }, "blah: expected [AsyncGeneratorFunction] not to be an asyncgeneratorfunction");
@@ -456,8 +491,8 @@ describe('expect', function () {
     err(function(){
       expect(new Foo(), 'blah').to.an.instanceof(1);
     }, "blah: The instanceof assertion needs a constructor but Number was given.");
-    err(function(){
 
+    err(function(){
       expect(new Foo()).to.an.instanceof('batman');
     }, "The instanceof assertion needs a constructor but String was given.");
 
diff --git a/test/should.js b/test/should.js
index 17429961..b1575141 100644
--- a/test/should.js
+++ b/test/should.js
@@ -442,6 +442,8 @@ describe('should', function() {
     ({}).should.be.a('object');
     ([]).should.be.a('array');
     (function() {}).should.be.a('function');
+    (async function*() {}).should.be.a('function');
+    (async function() {}).should.be.a('asyncfunction');
 
     if (typeof Symbol === 'function') {
       Symbol().should.be.a('symbol');