test: tests for observer computed

packages/observer/__tests__/computed.spec.ts

@@ -1 +1,139 @@
-describe('observer/computed', () => {})
+import { computed, observable, autorun } from '../src'
+
+describe('observer/computed', () => {
+  it('should return updated value', () => {
+    const value: any = observable({})
+    const cValue = computed(() => value.foo)
+    expect(cValue()).toBe(undefined)
+    value.foo = 1
+    expect(cValue()).toBe(1)
+  })
+
+  it('should compute lazily', () => {
+    const value: any = observable({})
+    const getter = jest.fn(() => value.foo)
+    const cValue = computed(getter)
+
+    // lazy
+    expect(getter).not.toHaveBeenCalled()
+
+    expect(cValue()).toBe(undefined)
+    expect(getter).toHaveBeenCalledTimes(1)
+
+    // should not compute again
+    cValue()
+    expect(getter).toHaveBeenCalledTimes(1)
+
+    // should not compute until needed
+    value.foo = 1
+    expect(getter).toHaveBeenCalledTimes(1)
+
+    // now it should compute
+    expect(cValue()).toBe(1)
+    expect(getter).toHaveBeenCalledTimes(2)
+
+    // should not compute again
+    cValue()
+    expect(getter).toHaveBeenCalledTimes(2)
+  })
+
+  it('should accept context', () => {
+    const value: any = observable({})
+    let callCtx, callArg
+    const getter = function(arg: any) {
+      callCtx = this
+      callArg = arg
+      return value.foo
+    }
+    const ctx = {}
+    const cValue = computed(getter, ctx)
+    cValue()
+    expect(callCtx).toBe(ctx)
+    expect(callArg).toBe(ctx)
+  })
+
+  it('should trigger autorun', () => {
+    const value: any = observable({})
+    const cValue = computed(() => value.foo)
+    let dummy
+    autorun(() => {
+      dummy = cValue()
+    })
+    expect(dummy).toBe(undefined)
+    value.foo = 1
+    expect(dummy).toBe(1)
+  })
+
+  it('should work when chained', () => {
+    const value: any = observable({ foo: 0 })
+    const c1 = computed(() => value.foo)
+    const c2 = computed(() => c1() + 1)
+    expect(c2()).toBe(1)
+    expect(c1()).toBe(0)
+    value.foo++
+    expect(c2()).toBe(2)
+    expect(c1()).toBe(1)
+  })
+
+  it('should trigger autorun when chained', () => {
+    const value: any = observable({ foo: 0 })
+    const getter1 = jest.fn(() => value.foo)
+    const getter2 = jest.fn(() => {
+      return c1() + 1
+    })
+    const c1 = computed(getter1)
+    const c2 = computed(getter2)
+
+    let dummy
+    autorun(() => {
+      dummy = c2()
+    })
+    expect(dummy).toBe(1)
+    expect(getter1).toHaveBeenCalledTimes(1)
+    expect(getter2).toHaveBeenCalledTimes(1)
+    value.foo++
+    expect(dummy).toBe(2)
+    // should not result in duplicate calls
+    expect(getter1).toHaveBeenCalledTimes(2)
+    expect(getter2).toHaveBeenCalledTimes(2)
+  })
+
+  it('should trigger autorun when chained (mixed invocations)', () => {
+    const value: any = observable({ foo: 0 })
+    const getter1 = jest.fn(() => value.foo)
+    const getter2 = jest.fn(() => {
+      return c1() + 1
+    })
+    const c1 = computed(getter1)
+    const c2 = computed(getter2)
+
+    let dummy
+    autorun(() => {
+      dummy = c1() + c2()
+    })
+    expect(dummy).toBe(1)
+
+    expect(getter1).toHaveBeenCalledTimes(1)
+    expect(getter2).toHaveBeenCalledTimes(1)
+    value.foo++
+    expect(dummy).toBe(3)
+    // should not result in duplicate calls
+    expect(getter1).toHaveBeenCalledTimes(2)
+    expect(getter2).toHaveBeenCalledTimes(2)
+  })
+
+  it('should no longer update when stopped', () => {
+    const value: any = observable({})
+    const cValue = computed(() => value.foo)
+    let dummy
+    autorun(() => {
+      dummy = cValue()
+    })
+    expect(dummy).toBe(undefined)
+    value.foo = 1
+    expect(dummy).toBe(1)
+    cValue.stop()
+    value.foo = 2
+    expect(dummy).toBe(1)
+  })
+})