diff --git a/tests/unit/splitter.spec.js b/tests/unit/splitter.spec.js
new file mode 100644
index 0000000..0ee12ee
--- /dev/null
+++ b/tests/unit/splitter.spec.js
@@ -0,0 +1,108 @@
+import { expect } from 'chai'
+import sinon from 'sinon'
+import splitter from '@/splitter'
+
+describe('splitter.js', () => {
+  afterEach(() => {
+    sinon.restore()
+  })
+
+  it('getCurrentMouseDrag', () => {
+    const container = document.createElement('div')
+    container.style.width = '100px'
+    container.style.height = '100px'
+    container.style.position = 'fixed'
+    container.style.top = '10px'
+    container.style.left = '20px'
+
+    document.body.appendChild(container)
+    
+    const event = new MouseEvent("mousemove", {
+      clientX: 70,
+      clientY: 80
+    })
+
+    const mouseDrag = splitter.getCurrentMouseDrag(event, container)
+    expect(mouseDrag.x).to.equal(50)
+    expect(mouseDrag.y).to.equal(70)
+  })
+
+  it("getCurrentDragPercentage - horisontal", () => {
+    sinon.stub(splitter, 'getCurrentMouseDrag').returns({ x: 50, y: 70 })
+
+    const event = {}
+    const isHorisontal = true
+    const container = document.createElement('div')
+    container.style.width = '200px'
+    container.style.height = '140px'
+
+    document.body.appendChild(container)
+
+    const dragPercentage = splitter.getCurrentDragPercentage(event, container, isHorisontal)
+    expect(dragPercentage).to.equal(50)
+  })
+
+  it("getCurrentDragPercentage - vertical", () => {
+    sinon.stub(splitter, 'getCurrentMouseDrag').returns({ x: 50, y: 70 })
+
+    const event = {}
+    const isHorisontal = false
+    const container = document.createElement('div')
+    container.style.width = '200px'
+    container.style.height = '140px'
+
+    document.body.appendChild(container)
+
+    const dragPercentage = splitter.getCurrentDragPercentage(event, container, isHorisontal)
+    expect(dragPercentage).to.equal(25)
+  })
+
+  it("calculateOffset", () => {
+    sinon.stub(splitter, 'getCurrentDragPercentage').returns(25)
+
+    const event = {}
+    const container = {}
+
+    const splitterInfo = {
+      container,
+      paneBeforeMax: 70,
+      paneAfterMax: 80,
+      isHorisontal: true
+    }
+    const offset = splitter.calculateOffset(event, splitterInfo)
+
+    expect(offset).to.equal(25)
+  })
+
+  it("calculateOffset prevents dragging beyond paneBefore max", () => {
+    sinon.stub(splitter, 'getCurrentDragPercentage').returns(75)
+
+    const event = {}
+    const container = {}
+    const splitterInfo = {
+      container,
+      paneBeforeMax: 70,
+      paneAfterMax: 80,
+      isHorisontal: true
+    }
+    const offset = splitter.calculateOffset(event, splitterInfo)
+
+    expect(offset).to.equal(70)
+  })
+
+  it("calculateOffset prevents dragging beyond paneAfter max", () => {
+    sinon.stub(splitter, 'getCurrentDragPercentage').returns(10)
+
+    const event = {}
+    const container = {}
+    const splitterInfo = {
+      container,
+      paneBeforeMax: 70,
+      paneAfterMax: 80,
+      isHorisontal: true
+    }
+    const offset = splitter.calculateOffset(event, splitterInfo)
+
+    expect(offset).to.equal(20)
+  })
+})