fix: should throw when mutate failed (vercel#557)

huozhi · web-flow · commit c5df6a5e49f8 · 2020-07-26T00:16:16.000+08:00
diff --git a/src/use-swr.ts b/src/use-swr.ts
@@ -139,9 +139,11 @@ const mutate: mutateInterface = async (
       promises.push(updaters[i](!!shouldRevalidate, data, error, i > 0))
     }
     // return new updated value
-    return Promise.all(promises).then(() => cache.get(key))
+    return Promise.all(promises).then(() => {
+      if (error) throw error
+      return cache.get(key)
+    })
   }
-
   // throw error or return data to be used by caller of mutate
   if (error) throw error
   return data
diff --git a/test/use-swr.test.tsx b/test/use-swr.test.tsx
@@ -1292,7 +1292,7 @@ describe('useSWR - local mutation', () => {
   })
 
   it('should update error in cache when mutate failed with error', async () => {
-    let value = 0
+    const value = 0
     const key = 'mutate-4'
     const message = 'mutate-error'
     function Page() {
@@ -1303,21 +1303,32 @@ describe('useSWR - local mutation', () => {
     await waitForDomChange({ container })
     expect(container.firstChild.textContent).toMatchInlineSnapshot(`"data: 0"`)
     await act(async () => {
-      await mutate(
-        key,
-        () => {
-          throw new Error(message)
-        },
-        false
-      )
+      // mutate error will be thrown, add try catch to avoid crashing
+      try {
+        await mutate(
+          key,
+          () => {
+            throw new Error(message)
+          },
+          false
+        )
+      } catch (e) {
+        // do nothing
+      }
     })
 
     const [, , keyErr] = cache.serializeKey(key)
-    const error = cache.get(keyErr)
-    expect(error.message).toMatchInlineSnapshot(`"${message}"`)
+    let cacheError = cache.get(keyErr)
+    expect(cacheError.message).toMatchInlineSnapshot(`"${message}"`)
     expect(container.firstChild.textContent).toMatchInlineSnapshot(
       `"${message}"`
     )
+    // if mutate succeed, error should be cleared
+    await act(async () => {
+      await mutate(key, value, false)
+    })
+    cacheError = cache.get(keyErr)
+    expect(cacheError).toMatchInlineSnapshot(`undefined`)
   })
 })
 

Original file line number	Diff line number	Diff line change
`@@ -139,9 +139,11 @@ const mutate: mutateInterface = async (`
`139`	`139`	`promises.push(updaters[i](!!shouldRevalidate, data, error, i > 0))`
`140`	`140`	`}`
`141`	`141`	`// return new updated value`
`142`		`- return Promise.all(promises).then(() => cache.get(key))`
	`142`	`+ return Promise.all(promises).then(() => {`
	`143`	`+ if (error) throw error`
	`144`	`+ return cache.get(key)`
	`145`	`+ })`
`143`	`146`	`}`
`144`		`-`
`145`	`147`	`// throw error or return data to be used by caller of mutate`
`146`	`148`	`if (error) throw error`
`147`	`149`	`return data`