initial commit

src/features/counter/counterSlice.spec.ts

@@ -0,0 +1,34 @@
+import counterReducer, {
+  CounterState,
+  increment,
+  decrement,
+  incrementByAmount,
+} from "./counterSlice"
+
+describe("counter reducer", () => {
+  const initialState: CounterState = {
+    value: 3,
+    status: "idle",
+  }
+  it("should handle initial state", () => {
+    expect(counterReducer(undefined, { type: "unknown" })).toEqual({
+      value: 0,
+      status: "idle",
+    })
+  })
+
+  it("should handle increment", () => {
+    const actual = counterReducer(initialState, increment())
+    expect(actual.value).toEqual(4)
+  })
+
+  it("should handle decrement", () => {
+    const actual = counterReducer(initialState, decrement())
+    expect(actual.value).toEqual(2)
+  })
+
+  it("should handle incrementByAmount", () => {
+    const actual = counterReducer(initialState, incrementByAmount(2))
+    expect(actual.value).toEqual(5)
+  })
+})