From a8b846469390dfe18b0f552159f935ad6c85aa9a Mon Sep 17 00:00:00 2001
From: Eduardo San Martin Morote <posva13@gmail.com>
Date: Mon, 23 Nov 2020 13:18:09 +0100
Subject: [PATCH 1/2] feat: add warn

---
 src/apis/index.ts      |  1 +
 src/apis/warn.ts       | 12 ++++++++++++
 src/env.d.ts           |  2 +-
 src/utils/utils.ts     |  2 +-
 test/apis/warn.spec.js | 25 +++++++++++++++++++++++++
 5 files changed, 40 insertions(+), 2 deletions(-)
 create mode 100644 src/apis/warn.ts
 create mode 100644 test/apis/warn.spec.js

diff --git a/src/apis/index.ts b/src/apis/index.ts
index bf2e31e2..d1821026 100644
--- a/src/apis/index.ts
+++ b/src/apis/index.ts
@@ -30,3 +30,4 @@ export { useCSSModule } from './useCssModule'
 export { createApp } from './createApp'
 export { nextTick } from './nextTick'
 export { createElement as h } from './createElement'
+export { warn } from './warn'
diff --git a/src/apis/warn.ts b/src/apis/warn.ts
new file mode 100644
index 00000000..2bb5236f
--- /dev/null
+++ b/src/apis/warn.ts
@@ -0,0 +1,12 @@
+import { getCurrentInstance } from '../runtimeContext'
+import { warn as vueWarn } from '../utils'
+
+/**
+ * Displays a warning message (using console.error) with a stack trace if the
+ * function is called inside of active component.
+ *
+ * @param message warning message to be displayed
+ */
+export function warn(message: string) {
+  vueWarn(message, getCurrentInstance())
+}
diff --git a/src/env.d.ts b/src/env.d.ts
index 161e9a67..8e362480 100644
--- a/src/env.d.ts
+++ b/src/env.d.ts
@@ -19,7 +19,7 @@ declare module 'vue/types/vue' {
   interface VueConstructor {
     observable<T>(x: any): T
     util: {
-      warn(msg: string, vm?: Vue)
+      warn(msg: string, vm?: Vue | null)
       defineReactive(
         obj: Object,
         key: string,
diff --git a/src/utils/utils.ts b/src/utils/utils.ts
index 0bffd6d7..2c4f4fc1 100644
--- a/src/utils/utils.ts
+++ b/src/utils/utils.ts
@@ -83,7 +83,7 @@ export function isUndef(v: any): boolean {
   return v === undefined || v === null
 }
 
-export function warn(msg: string, vm?: Vue) {
+export function warn(msg: string, vm?: Vue | null) {
   Vue.util.warn(msg, vm)
 }
 
diff --git a/test/apis/warn.spec.js b/test/apis/warn.spec.js
new file mode 100644
index 00000000..ab9401fb
--- /dev/null
+++ b/test/apis/warn.spec.js
@@ -0,0 +1,25 @@
+const Vue = require('vue/dist/vue.common.js')
+const { warn: apiWarn } = require('../../src')
+
+describe('api/warn', () => {
+  beforeEach(() => {
+    warn = jest.spyOn(global.console, 'error').mockImplementation(() => null)
+  })
+  afterEach(() => {
+    warn.mockRestore()
+  })
+
+  it('should work', () => {
+    new Vue({
+      setup() {
+        apiWarn('warned')
+      },
+      template: `<div></div>`,
+    }).$mount()
+
+    expect(warn).toHaveBeenCalled()
+    expect(warn.mock.calls[0][0]).toMatch(
+      /\[Vue warn\]: warned.?[\s\S]*\(found in <Root>\)/
+    )
+  })
+})

From eaf03df12d4973fad0401b85f5cb4e818d03ef92 Mon Sep 17 00:00:00 2001
From: Eduardo San Martin Morote <posva13@gmail.com>
Date: Mon, 23 Nov 2020 13:20:19 +0100
Subject: [PATCH 2/2] test: add test for warn

---
 test/apis/warn.spec.js | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/test/apis/warn.spec.js b/test/apis/warn.spec.js
index ab9401fb..9ceb5fa9 100644
--- a/test/apis/warn.spec.js
+++ b/test/apis/warn.spec.js
@@ -9,7 +9,7 @@ describe('api/warn', () => {
     warn.mockRestore()
   })
 
-  it('should work', () => {
+  it('can be called inside a component', () => {
     new Vue({
       setup() {
         apiWarn('warned')
@@ -17,9 +17,16 @@ describe('api/warn', () => {
       template: `<div></div>`,
     }).$mount()
 
-    expect(warn).toHaveBeenCalled()
+    expect(warn).toHaveBeenCalledTimes(1)
     expect(warn.mock.calls[0][0]).toMatch(
-      /\[Vue warn\]: warned.?[\s\S]*\(found in <Root>\)/
+      /\[Vue warn\]: warned[\s\S]*\(found in <Root>\)/
     )
   })
+
+  it('can be called outside a component', () => {
+    apiWarn('warned')
+
+    expect(warn).toHaveBeenCalledTimes(1)
+    expect(warn).toHaveBeenCalledWith('[Vue warn]: warned')
+  })
 })