increase test coverage

extend test coverage

tests/unit/paint.test.js

@@ -0,0 +1,72 @@
+import { describe, expect, it } from 'vitest'
+import Paint from '../../packages/svgcanvas/core/paint.js'
+
+const createLinear = (id) => {
+  const grad = document.createElementNS('http://www.w3.org/2000/svg', 'linearGradient')
+  if (id) grad.id = id
+  grad.setAttribute('x1', '0')
+  grad.setAttribute('x2', '1')
+  return grad
+}
+
+const createRadial = (id) => {
+  const grad = document.createElementNS('http://www.w3.org/2000/svg', 'radialGradient')
+  if (id) grad.id = id
+  grad.setAttribute('cx', '0.5')
+  grad.setAttribute('cy', '0.5')
+  return grad
+}
+
+describe('Paint', () => {
+  it('defaults to an empty paint when no options are provided', () => {
+    const paint = new Paint()
+    expect(paint.type).toBe('none')
+    expect(paint.alpha).toBe(100)
+    expect(paint.solidColor).toBeNull()
+    expect(paint.linearGradient).toBeNull()
+    expect(paint.radialGradient).toBeNull()
+  })
+
+  it('copies a solid color paint including alpha', () => {
+    const base = new Paint({ solidColor: '#00ff00', alpha: 65 })
+    const copy = new Paint({ copy: base })
+
+    expect(copy.type).toBe('solidColor')
+    expect(copy.alpha).toBe(65)
+    expect(copy.solidColor).toBe('#00ff00')
+    expect(copy.linearGradient).toBeNull()
+    expect(copy.radialGradient).toBeNull()
+  })
+
+  it('copies gradients by cloning the underlying nodes', () => {
+    const linear = createLinear('lin1')
+    const base = new Paint({ linearGradient: linear })
+    const clone = new Paint({ copy: base })
+
+    expect(clone.type).toBe('linearGradient')
+    expect(clone.linearGradient).not.toBe(base.linearGradient)
+    expect(clone.linearGradient?.isEqualNode(base.linearGradient)).toBe(true)
+  })
+
+  it('resolves linked linear gradients via href/xlink:href', () => {
+    const referenced = createLinear('refGrad')
+    document.body.append(referenced)
+    const referencing = createLinear('linkGrad')
+    referencing.setAttribute('xlink:href', '#refGrad')
+
+    const paint = new Paint({ linearGradient: referencing })
+    expect(paint.type).toBe('linearGradient')
+    expect(paint.linearGradient).not.toBeNull()
+    expect(paint.linearGradient?.id).toBe('refGrad')
+  })
+
+  it('creates radial gradients from provided element when no href is set', () => {
+    const radial = createRadial('rad1')
+    const paint = new Paint({ radialGradient: radial })
+
+    expect(paint.type).toBe('radialGradient')
+    expect(paint.radialGradient).not.toBe(radial)
+    expect(paint.radialGradient?.id).toBe('rad1')
+    expect(paint.linearGradient).toBeNull()
+  })
+})