increase test coverage

extend test coverage

tests/unit/dataStorage.test.js

@@ -0,0 +1,34 @@
+import { describe, expect, it } from 'vitest'
+import dataStorage from '../../packages/svgcanvas/core/dataStorage.js'
+
+describe('dataStorage', () => {
+  it('stores, checks and retrieves keyed values per element', () => {
+    const el1 = document.createElement('div')
+    const el2 = document.createElement('div')
+
+    dataStorage.put(el1, 'color', 'red')
+    dataStorage.put(el1, 'count', 3)
+    dataStorage.put(el2, 'color', 'blue')
+
+    expect(dataStorage.has(el1, 'color')).toBe(true)
+    expect(dataStorage.has(el1, 'missing')).toBe(false)
+    expect(dataStorage.get(el1, 'color')).toBe('red')
+    expect(dataStorage.get(el1, 'count')).toBe(3)
+    expect(dataStorage.get(el2, 'color')).toBe('blue')
+  })
+
+  it('removes values and cleans up empty element maps', () => {
+    const el = document.createElement('span')
+    dataStorage.put(el, 'foo', 1)
+    dataStorage.put(el, 'bar', 2)
+
+    expect(dataStorage.remove(el, 'foo')).toBe(true)
+    expect(dataStorage.has(el, 'foo')).toBe(false)
+    expect(dataStorage.get(el, 'bar')).toBe(2)
+
+    // Removing the last key should drop the element from storage entirely.
+    expect(dataStorage.remove(el, 'bar')).toBe(true)
+    expect(dataStorage.has(el, 'bar')).toBe(false)
+    expect(dataStorage.get(el, 'bar')).toBeUndefined()
+  })
+})