fix: deepMerge | remove duplicates when merging arrays

src/utilities/deepMerge.ts

@@ -19,7 +19,7 @@ const deepMerge = (target, source) => {
     const sourceValue = source[key]
     // merge both values
     if (Array.isArray(targetValue) && Array.isArray(sourceValue)) {
-      target[key] = targetValue.concat(sourceValue)
+      target[key] = [...new Set(targetValue.concat(sourceValue))]
     } else if (isObject(targetValue) && isObject(sourceValue)) {
       target[key] = deepMerge(Object.assign({}, targetValue), sourceValue)
     } else {

tests/unit/deepMerge.test.ts

@@ -1,44 +1,60 @@
+// deepMerge.test.ts
 import deepMerge from '@utils/deepMerge'
 
 describe('deepMerge', () => {
-  test('merge objects', () => {
-    expect(deepMerge(
-      {
-        id: 'not visible',
-        type: 'unique',
-        nested: {
-          stay: 'still here',
-          override: 'not here',
-          merged: [2]
-        }
-      },
-      {
-        id: 'visible',
-        nested: {
-          override: 'new value',
-          merged: ['test']
-        },
-        description: 'from second'
-      }
-    )).toStrictEqual(
-      {
-        id: 'visible',
-        type: 'unique',
-        nested: {
-          stay: 'still here',
-          override: 'new value',
-          merged: [2, 'test']
-        },
-        description: 'from second'
-      }
-    )
-  })
-
-  test('argument 1 is string, return source', () => {
-    expect(deepMerge('test', { value: 1 })).toStrictEqual({ value: 1 })
-  })
-
-  test('argument 2 is string, return source', () => {
-    expect(deepMerge({ value: 1 }, 'test')).toStrictEqual('test')
+  it('should merge two objects', () => {
+    const target = { a: 1, b: 2 }
+    const source = { b: 3, c: 4 }
+    const result = deepMerge(target, source)
+    expect(result).toEqual({ a: 1, b: 3, c: 4 })
+  })
+
+  it('should merge nested objects', () => {
+    const target = { a: { b: 1 } }
+    const source = { a: { c: 2 } }
+    const result = deepMerge(target, source)
+    expect(result).toEqual({ a: { b: 1, c: 2 } })
+  })
+
+  it('should merge arrays without duplicates', () => {
+    const target = { a: [1, 2] }
+    const source = { a: [2, 3] }
+    const result = deepMerge(target, source)
+    expect(result).toEqual({ a: [1, 2, 3] })
+  })
+
+  it('should overwrite non-object values', () => {
+    const target = { a: 1 }
+    const source = { a: 2 }
+    const result = deepMerge(target, source)
+    expect(result).toEqual({ a: 2 })
+  })
+
+  it('should return source if target is not an object', () => {
+    const target = null
+    const source = { a: 1 }
+    const result = deepMerge(target, source)
+    expect(result).toEqual({ a: 1 })
+  })
+
+  it('should return source if source is not an object', () => {
+    const target = { a: 1 }
+    const source = null
+    const result = deepMerge(target, source)
+    expect(result).toEqual(null)
+  })
+
+  it('should handle empty objects', () => {
+    const target = {}
+    const source = {}
+    const result = deepMerge(target, source)
+    expect(result).toEqual({})
+  })
+
+  it('should handle empty arrays', () => {
+    const target = { a: [] }
+    const source = { a: [] }
+    const result = deepMerge(target, source)
+    expect(result).toEqual({ a: [] })
   })
 })