diff --git a/README.md b/README.md
index 66d2b43..7d80dc1 100644
--- a/README.md
+++ b/README.md
@@ -74,8 +74,8 @@ Not only does eltro allow you to use any assertion library of your own choosing,
  * `assert.notMatch(value, [message])`: Check if value does not match RegExp test.
  * `assert.isFulfilled(promise, [message])`: Assert the promise resolves.
  * `assert.isRejected(promise, [message])`: Assert the promise gets rejects.
- 
- # Asynchronous Code
+
+# Asynchronous Code
 
 Eltro supports any type of asynchronous code testing. It can either be done by adding a parameter to the function (usually done) that gets called once the tests done but eltro also supports promises.
 
@@ -133,6 +133,30 @@ t.test('async test', async function() {
 })
 ```
 
+# Spying and stubbing
+
+Inspired by sinon js, this library comes with pre-built simple sinon-like style spy() and stub()
+
+```node
+import { assert, spy, stub } from 'eltro'
+
+let myFunc = spy()
+let myStub = stub()
+
+myFunc(1)
+myFunc(2)
+myFunc(3)
+myStub.returns('world')
+let out = myStub('hello')
+
+assert.strictEqual(out, 'world')
+assert.strictEqual(myFunc.getCall(0), 1)
+assert.strictEqual(myFunc.getCall(1), 2)
+assert.strictEqual(myFunc.getCall(2), 3)
+assert.strictEqual(myFunc.callCount, 3)
+assert.strictEqual(myStub.callCount, 1)
+```
+
 # Api
 
 ### t.test(message, func)
@@ -227,6 +251,70 @@ t.describe('#anotherTest()', function() {
 })
 ```
 
+### t.beforeEach(func)
+
+Queue up the `func` to run before each test or groups within current active group.
+
+```node
+import { Eltro as t, assert} from 'eltro'
+
+t.beforeEach(function() {
+  // Prepare something before each of the following tests
+})
+
+t.describe('#myTest()', function() {
+  t.beforeEach(function() {
+    // Runs before every test in this group
+  })
+
+  t.test('true should always be true', function() {
+    assert.strictEqual(true, true)
+  })
+})
+
+t.describe('#anotherTest()', function() {
+  t.beforeEach(function() {
+    // Runs before every test in this group
+  })
+
+  t.test('false should always be false', function() {
+    assert.strictEqual(false, false)
+  })
+})
+```
+
+### t.afterEach(func)
+
+Queue up the `func` to run after every test or groups within current active group.
+
+```node
+import { Eltro as t, assert} from 'eltro'
+
+t.afterEach(function() {
+  // After we finish each individual test below, this gets run
+})
+
+t.describe('#myTest()', function() {
+  t.afterEach(function() {
+    // Runs after each text in this group
+  })
+
+  t.test('true should always be true', function() {
+    assert.strictEqual(true, true)
+  })
+})
+
+t.describe('#anotherTest()', function() {
+  t.afterEach(function() {
+    // Runs after each text in this group
+  })
+
+  t.test('false should always be false', function() {
+    assert.strictEqual(false, false)
+  })
+})
+```
+
 ### t.only()
 
 Eltro supports exclusivity when running tests. When specified, only tests marked with only will be run.
@@ -305,3 +393,267 @@ or like so:
 ```node
 t.timeout(5000).test('A long test', async function() { ... })
 ```
+
+# Assert
+
+Eltro comes with an extended version of node's built-in assertion library.
+You can start using them by simply importing it with eltro test runner:
+
+```node
+import { assert } from 'eltro'
+```
+
+
+### assert.notOk(value[, message])
+
+Tests if value is a falsy value using `Boolean(value) == false`
+
+```node
+assert.notOk(false)      // ok
+assert.notOk(null)       // ok
+assert.notOk(undefined)  // ok
+assert.notOk([])         // throws
+```
+
+### assert.match(value, test[, message])
+
+Test if the string value has a regex match of test
+
+```node
+assert.match('asdf', /a/)            // ok
+assert.match('hello world', /hello/) // ok
+assert.match('something', /else/)    // throws
+```
+
+### assert.notMatch(value, test[, message])
+
+Test if the string value does not regex match the test
+
+```node
+assert.notMatch('asdf', /b/)            // ok
+assert.notMatch('something', /else/)    // ok
+assert.notMatch('hello world', /hello/) // throws
+```
+
+### assert.isFulfilled(promise[, message])
+
+Tests to make sure the promise gets fulfilled successfully and
+returns the final result.
+
+```node
+await assert.isFulfilled(Promise.resolve(null))       // ok
+await assert.isFulfilled(() => { throw new Error() }) // throws
+```
+
+### assert.isRejected(promise[, message])
+
+Tests to make sure the promise gets rejected and returns the error
+or value that was rejected
+
+```node
+let val = await assert.isRejected(Promise.reject('asdf'))             // ok
+assert.strictEqual(val, 'asdf')
+
+let err = await assert.isRejected(() => { throw new Error('hello') }) // ok
+assert.strictEqual(err.message, 'hello')
+```
+
+# Sinon-like spy()/stub()
+
+Using sinon-inspired mechanics for spying on calls as well as being able
+to stub existing functionality, eltro comes with a handy little copy-cat.
+
+Functionality-wise, the difference between spy() and stub() are none.
+Both will do the exact same thing, the naming differention is simply to allow
+the resulting code to speak about its purpose.
+
+To create a stub or a spy, simply import it and call it like so:
+
+```node
+import { spy, stub } from 'eltro'
+
+let spying = spy()
+let fn = stub()
+```
+
+Each call to stub or spy is an array list of the passed-on arguments:
+
+```node
+let spying = spy()
+spying('hello', 'world')
+
+assert.strictEqual(spying.lastCall[0], 'hello')
+assert.strictEqual(spying.lastCall[1], 'world')
+```
+
+### lastCall
+
+Returns the last call that was made to sinon and stub:
+
+```node
+let spying = spy()
+spying('a')
+spying('b')
+spying('c')
+
+assert.strictEqual(spying.lastCall[0], 'c')
+```
+
+### called
+
+Boolean variable that gets flipped once it's called at least once
+
+```node
+let spying = spy()
+assert.strictEqual(spying.called, false)
+spying('a')
+assert.strictEqual(spying.called, true)
+spying('b')
+spying('c')
+assert.strictEqual(spying.called, true)
+```
+
+### callCount
+
+The number of times it's been called
+
+```node
+let spying = spy()
+assert.strictEqual(spying.callCount, 0)
+spying('a')
+assert.strictEqual(spying.callCount, 1)
+spying('b')
+spying('c')
+assert.strictEqual(spying.callCount, 3)
+```
+
+### returns(data)
+
+Specifies what value the stub or spy should return when it gets called.
+
+```node
+let fn = stub()
+fn.returns('a')
+
+assert.strictEqual(fn(), 'a')
+assert.strictEqual(fn(), 'a')
+```
+
+### throws(data)
+
+Specifies what value the stub or spy should throw when it gets called.
+
+```node
+let fn = stub()
+fn.throws(new Error('b'))
+
+try {
+  fn()
+} catch (err) {
+  assert.strictEqual(fn(), 'b')
+}
+```
+
+### resolves(data)
+
+Specifies what value the stub or spy should return wrapped in a promise.
+
+```node
+let fn = stub()
+fn.resolves('a')
+
+fn().then(function(data) {
+  assert.strictEqual(data, 'a')
+})
+```
+
+### rejects(data)
+
+Specifies what value the stub or spy should reject, wrapped in a promise.
+
+```node
+let fn = stub()
+fn.rejects('nope')
+
+fn().catch(function(data) {
+  assert.strictEqual(data, 'nope')
+})
+```
+
+### returnWith(fn)
+
+Specify custom function to be called whenever the stub or spy gets called.
+
+```node
+let fn = stub()
+fn.returnWith(function(a) {
+  if (a === 'a') return true
+  return false
+})
+
+assert.strictEqual(fn(), false)
+assert.strictEqual(fn('b'), false)
+assert.strictEqual(fn('a'), true)
+assert.strictEqual(fn.callCount, 3)
+```
+
+### getCall(index)
+### getCallN(num)
+
+Get a specific call. The `getCall` gets a zero-based index call while the `getCallN(num)` gets the more natural number call
+
+```node
+let spying = spy()
+spying('a')
+spying('b')
+spying('c')
+assert.strictEqual(spying.getCall(0), 'a')
+assert.strictEqual(spying.getCall(1), 'b')
+assert.strictEqual(spying.getCallN(1), 'a')
+assert.strictEqual(spying.getCallN(2), 'b')
+```
+
+### onCall(index)
+### onCallN(num)
+
+Overwrite behavior for a specific numbered call. Just like with getCall/getCallN, the onCall is zero-indexed number of the call you want to specify custom behavior while onCallN is the more natural number of the call you want to specify custom behavior.
+
+Note, when called with null, it specifies the default behavior.
+
+```node
+let fnOne = stub()
+let fnTwo = stub()
+
+fnOne.onCall(1).returns('b')
+     .onCall().returns('a')
+
+fnTwo.onCallN(2).returns('two')
+     .onCallN().returns('one')
+
+assert.strictEqual(fnOne(), 'a')
+assert.strictEqual(fnOne(), 'b')
+assert.strictEqual(fnOne(), 'a')
+
+assert.strictEqual(fnTwo(), 'one')
+assert.strictEqual(fnTwo(), 'two')
+assert.strictEqual(fnTwo(), 'one')
+```
+
+### findCall(fn)
+
+Search for the first call when `fn(call)` returns `true`. Essentially a filter to search for a specific call that matches whatever call you're searching for.
+
+
+```node
+let evnt = stub()
+
+evnt('onclick', 'one')
+evnt('onerror', 'two')
+evnt('something', 'three')
+evnt('onpress', 'four')
+evnt('else', 'five')
+
+let foundPressCall = evnt.findCall(function(call) { return call[0] === 'onpress' })
+assert.strictEqual(foundPressCall[0], 'onpress')
+assert.strictEqual(foundPressCall[1], 'four')
+```
diff --git a/lib/sinon.mjs b/lib/sinon.mjs
index 616fac8..0623163 100644
--- a/lib/sinon.mjs
+++ b/lib/sinon.mjs
@@ -35,6 +35,13 @@ export function stub(returnFunc = null) {
   func.called = false
   func.callCount = 0
 
+  func.findCall = function(fn) {
+    for (let call of calls) {
+      if (fn(call)) return call
+    }
+    return null
+  }
+
   func.getCall = function(i) {
     return calls[i]
   }
diff --git a/test/sinon.test.mjs b/test/sinon.test.mjs
index ead55e2..bfa6951 100644
--- a/test/sinon.test.mjs
+++ b/test/sinon.test.mjs
@@ -96,6 +96,35 @@ import { spy, stub } from '../index.mjs'
       assert.strictEqual(spyer.thirdCall[0], assertThirdArgs[0])
       assert.strictEqual(spyer.thirdCall[1], assertThirdArgs[1])
     })
+    
+  
+    t.test('should support searching for a call', function() {
+      const assertFirstArgs = 'asdf'
+      const assertSecondArgs = { a: 1 }
+      const assertThirdArgs = [{ b: 1 }, { c: 2 }]
+      let spyer = tester()
+      assert.notOk(spyer.called)
+      
+      spyer(assertFirstArgs)
+      spyer(assertSecondArgs)
+      spyer(assertThirdArgs[0], assertThirdArgs[1])
+
+      let call = spyer.findCall((args) => args[0] === assertSecondArgs)
+      assert.strictEqual(spyer.secondCall, call)
+      assert.strictEqual(call[0], assertSecondArgs)
+      
+      call = spyer.findCall((args) => args[0].b === assertThirdArgs[0].b)
+      assert.strictEqual(spyer.thirdCall, call)
+      assert.strictEqual(call[0], assertThirdArgs[0])
+      assert.strictEqual(call[1], assertThirdArgs[1])
+      
+      call = spyer.findCall((args) => typeof args[0] === 'string')
+      assert.strictEqual(spyer.firstCall, call)
+      assert.strictEqual(call[0], assertFirstArgs)
+      
+      call = spyer.findCall(() => false)
+      assert.strictEqual(call, null)
+    })
   })
 })