Merge pull request #1087 from votingworks/style/lint/gts-use-optional…

…-properties

style(lint): use optional properties/fields/params

apps/bmd/src/AppRoot.tsx

@@ -92,7 +92,7 @@ interface CardState {
   pauseProcessingUntilNoCardPresent: boolean
   showPostVotingInstructions?: PostVotingInstructions
   voterCardCreatedAt: number
-  tallyOnCard?: Optional<PrecinctScannerCardTally>
+  tallyOnCard?: PrecinctScannerCardTally
 }
 
 interface UserState {

apps/bmd/src/pages/PollWorkerScreen.tsx

@@ -1,12 +1,7 @@
 import { DateTime } from 'luxon'
 import React, { useState, useEffect, useCallback } from 'react'
 
-import {
-  ElectionDefinition,
-  Optional,
-  Tally,
-  VotingMethod,
-} from '@votingworks/types'
+import { ElectionDefinition, Tally, VotingMethod } from '@votingworks/types'
 import {
   Button,
   ButtonList,
@@ -60,7 +55,7 @@ interface Props {
   machineConfig: MachineConfig
   printer: Printer
   togglePollsOpen: () => void
-  tallyOnCard: Optional<PrecinctScannerCardTally>
+  tallyOnCard?: PrecinctScannerCardTally
   clearTalliesOnCard: () => Promise<void>
 }
 

apps/bmd/src/utils/ScreenReader/AriaScreenReader.ts

@@ -146,9 +146,7 @@ export default class AriaScreenReader implements ScreenReader {
       : this.describeElement(node)
   }
 
-  private cleanDescription(
-    description: string | undefined
-  ): string | undefined {
+  private cleanDescription(description?: string): string | undefined {
     if (!description) {
       return
     }

apps/bsd/src/AppRoot.tsx

@@ -123,7 +123,7 @@ const App = ({ card, hardware }: AppRootProps): JSX.Element => {
     setMarkThresholds(await config.getMarkThresholdOverrides())
   }, [])
 
-  const updateElectionDefinition = async (e: Optional<ElectionDefinition>) => {
+  const updateElectionDefinition = async (e?: ElectionDefinition) => {
     setElectionDefinition(e)
     setElectionJustLoaded(true)
   }
@@ -264,7 +264,7 @@ const App = ({ card, hardware }: AppRootProps): JSX.Element => {
   }, [history, isTestMode, refreshConfig])
 
   const setMarkThresholdOverrides = useCallback(
-    async (markThresholdOverrides: Optional<MarkThresholds>) => {
+    async (markThresholdOverrides?: MarkThresholds) => {
       await config.setMarkThresholdOverrides(markThresholdOverrides)
       await refreshConfig()
       history.replace('/')

apps/bsd/src/screens/AdvancedOptionsScreen.tsx

@@ -1,8 +1,4 @@
-import {
-  ElectionDefinition,
-  MarkThresholds,
-  Optional,
-} from '@votingworks/types'
+import { ElectionDefinition, MarkThresholds } from '@votingworks/types'
 import React, { useCallback, useEffect, useState, useContext } from 'react'
 import Button from '../components/Button'
 import LinkButton from '../components/LinkButton'
@@ -23,10 +19,8 @@ interface Props {
   isTestMode: boolean
   isTogglingTestMode: boolean
   toggleTestMode: () => Promise<void>
-  setMarkThresholdOverrides: (
-    markThresholds: Optional<MarkThresholds>
-  ) => Promise<void>
-  markThresholds: Optional<MarkThresholds>
+  setMarkThresholdOverrides: (markThresholds?: MarkThresholds) => Promise<void>
+  markThresholds?: MarkThresholds
   electionDefinition: ElectionDefinition
 }
 

apps/bsd/test/renderInAppContext.tsx

@@ -8,7 +8,7 @@ import { Router } from 'react-router-dom'
 import AppContext from '../src/contexts/AppContext'
 
 interface RenderInAppContextParams {
-  route?: string | undefined
+  route?: string
   history?: MemoryHistory<any> // eslint-disable-line @typescript-eslint/no-explicit-any
   electionDefinition?: ElectionDefinition
   machineId?: string

apps/election-manager/src/contexts/AppContext.ts

@@ -3,7 +3,6 @@ import {
   ElectionDefinition,
   FullElectionTally,
   FullElectionExternalTally,
-  Optional,
   UserSession,
 } from '@votingworks/types'
 import { usbstick, NullPrinter, Printer } from '@votingworks/utils'
@@ -48,7 +47,7 @@ export interface AppContextInterface {
   ) => Promise<void>
   setIsTabulationRunning: React.Dispatch<React.SetStateAction<boolean>>
   generateExportableTallies: () => ExportableTallies
-  currentUserSession: Optional<UserSession>
+  currentUserSession?: UserSession
   attemptToAuthenticateAdminUser: (passcode: string) => boolean
   lockMachine: () => void
   machineConfig: MachineConfig

apps/election-manager/src/screens/DefinitionContestsScreen.tsx

@@ -89,7 +89,7 @@ const TextField = ({
   pattern?: string
   step?: number
   type?: 'text' | 'textarea' | 'number'
-  value: string | number | undefined
+  value?: string | number
 }) => (
   <StyledField>
     <label htmlFor={name}>

apps/election-manager/test/renderInAppContext.tsx

@@ -10,7 +10,6 @@ import {
   ElectionDefinition,
   FullElectionTally,
   FullElectionExternalTally,
-  Optional,
   UserSession,
 } from '@votingworks/types'
 import { usbstick, NullPrinter, Printer } from '@votingworks/utils'
@@ -35,7 +34,7 @@ export const eitherNeitherElectionDefinition = {
 }
 
 interface RenderInAppContextParams {
-  route?: string | undefined
+  route?: string
   history?: MemoryHistory<any> // eslint-disable-line @typescript-eslint/no-explicit-any
   castVoteRecordFiles?: CastVoteRecordFiles
   electionDefinition?: ElectionDefinition
@@ -63,7 +62,7 @@ interface RenderInAppContextParams {
   ) => Promise<void>
   fullElectionExternalTallies?: FullElectionExternalTally[]
   generateExportableTallies?: () => ExportableTallies
-  currentUserSession?: Optional<UserSession>
+  currentUserSession?: UserSession
   attemptToAuthenticateAdminUser?: () => boolean
   lockMachine?: () => undefined
   machineConfig?: MachineConfig

apps/module-scan/src/importer.ts

@@ -5,7 +5,6 @@ import {
   ElectionDefinition,
   MarkAdjudications,
   MarkThresholds,
-  Optional,
   PageInterpretation,
 } from '@votingworks/types'
 import { ScannerStatus, ScanStatus } from '@votingworks/types/api/module-scan'
@@ -69,8 +68,8 @@ export async function saveImages(
 export default class Importer {
   private workspace: Workspace
   private scanner: Scanner
-  private sheetGenerator: BatchControl | undefined
-  private batchId: string | undefined
+  private sheetGenerator?: BatchControl
+  private batchId?: string
   private workerPool?: WorkerPool<workers.Input, workers.Output>
   private workerPoolProvider: () => WorkerPool<workers.Input, workers.Output>
   private interpreterReady = true
@@ -191,7 +190,7 @@ export default class Importer {
   }
 
   async setMarkThresholdOverrides(
-    markThresholds: Optional<MarkThresholds>
+    markThresholds?: MarkThresholds
   ): Promise<void> {
     debug('setting mark thresholds overrides to %s', markThresholds)
     await this.workspace.store.setMarkThresholdOverrides(markThresholds)

apps/module-scan/src/store.ts

@@ -413,7 +413,7 @@ export default class Store {
    * in the election definition.
    */
   async setMarkThresholdOverrides(
-    markThresholds: Optional<MarkThresholds>
+    markThresholds?: MarkThresholds
   ): Promise<void> {
     await this.setConfig(ConfigKey.MarkThresholdOverrides, markThresholds)
   }

apps/precinct-scanner/src/api/config.ts

@@ -125,7 +125,7 @@ export async function getCurrentPrecinctId(): Promise<
 }
 
 export async function setCurrentPrecinctId(
-  precinctId: Precinct['id'] | undefined
+  precinctId?: Precinct['id']
 ): Promise<void> {
   if (!precinctId) {
     await del('/config/precinct')

apps/precinct-scanner/src/components/ExportResultsModal.test.tsx

@@ -1,7 +1,6 @@
 import React from 'react'
 
 import { render, fireEvent, waitFor } from '@testing-library/react'
-import fileDownload from 'js-file-download'
 import {
   electionSampleDefinition as electionDefinition,
   electionSampleDefinition,

libs/eslint-plugin-vx/docs/rules/gts-use-optionals.md

@@ -0,0 +1,38 @@
+# Use optional fields (on interfaces or classes) and parameters rather than a `|undefined` type. (`vx/gts-use-optionals`)
+
+This rule is from
+[Google TypeScript Style Guide section "Optionals vs `|undefined` type"](https://google.github.io/styleguide/tsguide.html#optionals-vs-undefined-type):
+
+> TypeScript supports a special construct for optional parameters and fields,
+> using `?`. Optional parameters implicitly include |undefined in their type.
+> However, they are different in that they can be left out when constructing a
+> value or calling a method. Use optional fields (on interfaces or classes) and
+> parameters rather than a `|undefined` type.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```ts
+interface CoffeeOrder {
+  sugarCubes: number
+  milk: Whole | LowFat | HalfHalf | undefined
+}
+
+function pourCoffee(volume: Milliliter | undefined) {
+  /* … */
+}
+```
+
+Examples of **correct** code for this rule:
+
+```ts
+interface CoffeeOrder {
+  sugarCubes: number
+  milk?: Whole | LowFat | HalfHalf
+}
+
+function pourCoffee(volume?: Milliliter) {
+  /* … */
+}
+```

libs/eslint-plugin-vx/src/configs/recommended.ts

@@ -43,6 +43,7 @@ export = {
     'vx/gts-no-private-fields': 'error',
     'vx/gts-no-public-modifier': 'error',
     'vx/gts-parameter-properties': 'error',
+    'vx/gts-use-optionals': 'error',
     'vx/no-array-sort-mutation': 'error',
     'vx/no-assert-truthiness': 'error',
     'vx/no-floating-results': ['error', { ignoreVoid: true }],