refactor: move mockWarn utility to @vue/shared

close #652

packages/shared/src/index.ts

@@ -5,6 +5,7 @@ export * from './patchFlags'
 export * from './globalsWhitelist'
 export * from './codeframe'
 export * from './domTagConfig'
+export * from './mockWarn'
 
 export const EMPTY_OBJ: { readonly [key: string]: any } = __DEV__
   ? Object.freeze({})

packages/shared/src/mockWarn.ts

@@ -0,0 +1,103 @@
+declare global {
+  namespace jest {
+    interface Matchers<R, T> {
+      toHaveBeenWarned(): R
+      toHaveBeenWarnedLast(): R
+      toHaveBeenWarnedTimes(n: number): R
+    }
+  }
+}
+
+export function mockWarn() {
+  expect.extend({
+    toHaveBeenWarned(received: string) {
+      asserted.add(received)
+      const passed = warn.mock.calls.some(
+        args => args[0].indexOf(received) > -1
+      )
+      if (passed) {
+        return {
+          pass: true,
+          message: () => `expected "${received}" not to have been warned.`
+        }
+      } else {
+        const msgs = warn.mock.calls.map(args => args[0]).join('\n - ')
+        return {
+          pass: false,
+          message: () =>
+            `expected "${received}" to have been warned.\n\nActual messages:\n\n - ${msgs}`
+        }
+      }
+    },
+
+    toHaveBeenWarnedLast(received: string) {
+      asserted.add(received)
+      const passed =
+        warn.mock.calls[warn.mock.calls.length - 1][0].indexOf(received) > -1
+      if (passed) {
+        return {
+          pass: true,
+          message: () => `expected "${received}" not to have been warned last.`
+        }
+      } else {
+        const msgs = warn.mock.calls.map(args => args[0]).join('\n - ')
+        return {
+          pass: false,
+          message: () =>
+            `expected "${received}" to have been warned last.\n\nActual messages:\n\n - ${msgs}`
+        }
+      }
+    },
+
+    toHaveBeenWarnedTimes(received: string, n: number) {
+      asserted.add(received)
+      let found = 0
+      warn.mock.calls.forEach(args => {
+        if (args[0].indexOf(received) > -1) {
+          found++
+        }
+      })
+
+      if (found === n) {
+        return {
+          pass: true,
+          message: () =>
+            `expected "${received}" to have been warned ${n} times.`
+        }
+      } else {
+        return {
+          pass: false,
+          message: () =>
+            `expected "${received}" to have been warned ${n} times but got ${found}.`
+        }
+      }
+    }
+  })
+
+  let warn: jest.SpyInstance
+  const asserted: Set<string> = new Set()
+
+  beforeEach(() => {
+    asserted.clear()
+    warn = jest.spyOn(console, 'warn')
+    warn.mockImplementation(() => {})
+  })
+
+  afterEach(() => {
+    const assertedArray = Array.from(asserted)
+    const nonAssertedWarnings = warn.mock.calls
+      .map(args => args[0])
+      .filter(received => {
+        return !assertedArray.some(assertedMsg => {
+          return received.indexOf(assertedMsg) > -1
+        })
+      })
+    warn.mockRestore()
+    if (nonAssertedWarnings.length) {
+      nonAssertedWarnings.forEach(warning => {
+        console.warn(warning)
+      })
+      throw new Error(`test case threw unexpected warnings.`)
+    }
+  })
+}