update AsyncView to work with swr's loading flag and support nullable…

src/async-data/AsyncView.tsx

@@ -2,16 +2,25 @@ import React, { ReactElement, ReactNode } from 'react'
 import { isFunction } from '../util'
 
 type LoadingFunction = () => ReactNode
-type SuccessFunction<Data> = (data: NonNullable<Data>) => ReactNode
+type SuccessFunction<Data> = (data: Data) => ReactNode
 type ErrorFunction<Error> = (error: NonNullable<Error>) => ReactNode
 
 type Props<Data, Error> = {
   data?: Data
   error?: Error
+  isLoading: boolean
   renderLoading?: ReactNode | LoadingFunction
-  renderSuccess: ReactNode | SuccessFunction<Data>
   renderError?: ReactNode | ErrorFunction<Error>
-}
+} & (
+  | {
+      allowMissingData: true
+      renderSuccess: ReactNode | SuccessFunction<Data>
+    }
+  | {
+      allowMissingData?: false
+      renderSuccess: ReactNode | SuccessFunction<NonNullable<Data>>
+    }
+)
 
 const AsyncView = <Data, Error>(
   props: Props<Data, Error>,
@@ -20,19 +29,34 @@ const AsyncView = <Data, Error>(
   const {
     data,
     error,
+    isLoading,
     renderLoading = null,
     renderSuccess,
     renderError = null,
+    allowMissingData = false,
   } = props
+
+  if (isLoading) {
+    return <>{isFunction(renderLoading) ? renderLoading() : renderLoading}</>
+  }
+
   if (error !== null && error !== undefined) {
     return <>{isFunction(renderError) ? renderError(error) : renderError}</>
-  } else if (data !== null && data !== undefined) {
-    return (
-      <>{isFunction(renderSuccess) ? renderSuccess(data) : renderSuccess}</>
+  }
+
+  if ((data === undefined || data === null) && !allowMissingData) {
+    throw new Error(
+      'Data passed into AsyncView was null or undefined. Use allowMissingData=true if this is intended.',
     )
-  } else {
-    return <>{isFunction(renderLoading) ? renderLoading() : renderLoading}</>
   }
+
+  return (
+    <>
+      {isFunction(renderSuccess)
+        ? renderSuccess(data as NonNullable<Data>)
+        : renderSuccess}
+    </>
+  )
 }
 
 export { AsyncView }

src/async-data/__test__/AsyncView.test.tsx

@@ -4,7 +4,7 @@ import { AsyncView } from '../AsyncView'
 
 type Data = {
   greeting: string
-}
+} | null
 
 type Error = {
   message: string
@@ -15,36 +15,76 @@ const Loading: React.FC = () => {
 }
 
 const Success: React.FC<{ data: Data }> = ({ data }) => {
-  return <>{data.greeting}</>
+  return <>{data?.greeting}</>
 }
 
 const Error: React.FC<{ error: Error }> = ({ error }) => {
   return <>{error.message}</>
 }
 
-function renderAsyncView(data?: Data, error?: Error): RenderResult {
+type RenderAsyncViewProps = {
+  isLoading: boolean
+  error?: Error
+  data?: Data
+  allowMissingData?: boolean
+}
+
+function renderAsyncView({
+  isLoading,
+  data,
+  error,
+  allowMissingData = false,
+}: RenderAsyncViewProps): RenderResult {
   return render(
-    <AsyncView<Data, Error>
+    <AsyncView
+      isLoading={isLoading}
       data={data}
       error={error}
+      allowMissingData={allowMissingData}
       renderLoading={<Loading />}
-      renderSuccess={(data) => <Success data={data} />}
+      renderSuccess={(data: unknown) => <Success data={data as Data} />}
       renderError={(error) => <Error error={error} />}
     />,
   )
 }
 
 test('should render loading if asyncState is loading for the first time', function () {
-  const { getByText } = renderAsyncView()
+  const { getByText } = renderAsyncView({ isLoading: true })
   expect(getByText(/loading/i)).toBeInTheDocument()
 })
 
 test('should render success if asyncState is successful', function () {
-  const { getByText } = renderAsyncView({ greeting: 'Hello' })
+  const { getByText } = renderAsyncView({
+    isLoading: false,
+    data: { greeting: 'Hello' },
+  })
   expect(getByText(/hello/i)).toBeInTheDocument()
 })
 
+test.each([null, undefined])(
+  'should throw asyncState is successful but data is missing',
+  function (value) {
+    expect(() => renderAsyncView({ isLoading: false, data: value })).toThrow()
+  },
+)
+
+test.each([null, undefined])(
+  'should render success if asyncState is successful but data is missing but allowed',
+  function (value) {
+    expect(() =>
+      renderAsyncView({
+        isLoading: false,
+        data: value,
+        allowMissingData: true,
+      }),
+    ).not.toThrow()
+  },
+)
+
 test('should render error if asyncState is error', function () {
-  const { getByText } = renderAsyncView(undefined, { message: 'Error' })
+  const { getByText } = renderAsyncView({
+    isLoading: false,
+    error: { message: 'Error' },
+  })
   expect(getByText(/error/i)).toBeInTheDocument()
 })

tsconfig.json

@@ -4,6 +4,6 @@
     "moduleResolution": "node",
     "skipLibCheck": true
   },
-  "exclude": ["node_modules", "dist", "**/__test__/*", "**/__tests__/*"],
+  "exclude": ["node_modules", "dist"],
   "include": ["**/*.ts", "**/*.tsx", "**/*.js"]
 }