[eslint] Prefer TypeScript interface over type aliases.

We have a mix of `type` and `interface` usage throughout our codebase,
that is sometimes difficult to follow and reason about. We should follow
the suggestion from the TypeScript PM and use `interface` consistently
where possible. This leads to better type display in errors and makes
our codebase easier to read (b/c consistency).

This CL adds the `@typescript-eslint/consistent-type-definitions`
ESLint rule to accomplish this.

Fixed: 387237537
Change-Id: Idb9e8275ddd8f633021d6cf1c933e2e55f980e45
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6152576
Auto-Submit: Nikolay Vitkov <nvitkov@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>

Author: Lightning00Blade

eslint.config.mjs

@@ -453,6 +453,8 @@ export default [
         },
       ],
 
+      '@typescript-eslint/consistent-type-definitions': ['error', 'interface'],
+
       'rulesdir/no-underscored-properties': 'error',
       'rulesdir/prefer-readonly-keyword': 'error',
       'rulesdir/inline-type-imports': 'error',

front_end/core/common/Console.ts

@@ -78,9 +78,9 @@ export const enum Events {
   MESSAGE_ADDED = 'messageAdded',
 }
 
-export type EventTypes = {
-  [Events.MESSAGE_ADDED]: Message,
-};
+export interface EventTypes {
+  [Events.MESSAGE_ADDED]: Message;
+}
 
 export const enum MessageLevel {
   INFO = 'info',

front_end/core/common/EventTarget.test.ts

@@ -16,13 +16,13 @@ const enum Events {
   UNION_EVENT = 'UnionEvent',
 }
 
-type TestEvents = {
-  [Events.VOID_EVENT]: void,
-  [Events.NUMBER_EVENT]: number,
-  [Events.KEY_VALUE_EVENT]: {key: string, value: number},
-  [Events.BOOLEAN_EVENT]: boolean,
-  [Events.UNION_EVENT]: string|null,
-};
+interface TestEvents {
+  [Events.VOID_EVENT]: void;
+  [Events.NUMBER_EVENT]: number;
+  [Events.KEY_VALUE_EVENT]: {key: string, value: number};
+  [Events.BOOLEAN_EVENT]: boolean;
+  [Events.UNION_EVENT]: string|null;
+}
 
 class TypedEventEmitter extends Common.ObjectWrapper.ObjectWrapper<TestEvents> {
   testValidArgumentTypes() {

front_end/core/common/EventTarget.ts

@@ -22,10 +22,10 @@ export function removeEventListeners(eventList: EventDescriptor[]): void {
 
 // This type can be used as the type parameter for `EventTarget`/`ObjectWrapper`
 // when the set of events is not known at compile time.
-export type GenericEvents = {
+export interface GenericEvents {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  [eventName: string]: any,
-};
+  [eventName: string]: any;
+}
 
 export type EventPayloadToRestParameters<Events, T extends keyof Events> = Events[T] extends void ? [] : [Events[T]];
 export type EventListener<Events, T extends keyof Events> = (arg0: EventTargetEvent<Events[T], Events>) => void;

front_end/core/host/AidaClient.ts

@@ -495,6 +495,6 @@ export const enum Events {
   AIDA_AVAILABILITY_CHANGED = 'aidaAvailabilityChanged',
 }
 
-export type EventTypes = {
-  [Events.AIDA_AVAILABILITY_CHANGED]: void,
-};
+export interface EventTypes {
+  [Events.AIDA_AVAILABILITY_CHANGED]: void;
+}

front_end/core/host/InspectorFrontendHostAPI.ts

@@ -204,36 +204,36 @@ export interface KeyDownEvent {
 // `EventTypes` is not used at runtime.
 // Please note that the "dispatch" side can't be type-checked as the dispatch is
 // done dynamically.
-export type EventTypes = {
-  [Events.AppendedToURL]: Platform.DevToolsPath.RawPathString|Platform.DevToolsPath.UrlString,
-  [Events.CanceledSaveURL]: Platform.DevToolsPath.UrlString,
-  [Events.ColorThemeChanged]: void,
-  [Events.ContextMenuCleared]: void,
-  [Events.ContextMenuItemSelected]: number,
-  [Events.DeviceCountUpdated]: number,
-  [Events.DevicesDiscoveryConfigChanged]: Adb.Config,
-  [Events.DevicesPortForwardingStatusChanged]: void,
-  [Events.DevicesUpdated]: void,
-  [Events.DispatchMessage]: string,
-  [Events.DispatchMessageChunk]: DispatchMessageChunkEvent,
-  [Events.EnterInspectElementMode]: void,
-  [Events.EyeDropperPickedColor]: EyeDropperPickedColorEvent,
-  [Events.FileSystemsLoaded]: DevToolsFileSystem[],
-  [Events.FileSystemRemoved]: Platform.DevToolsPath.RawPathString,
-  [Events.FileSystemAdded]: FileSystemAddedEvent,
-  [Events.FileSystemFilesChangedAddedRemoved]: FilesChangedEvent,
-  [Events.IndexingTotalWorkCalculated]: IndexingTotalWorkCalculatedEvent,
-  [Events.IndexingWorked]: IndexingWorkedEvent,
-  [Events.IndexingDone]: IndexingEvent,
-  [Events.KeyEventUnhandled]: KeyEventUnhandledEvent,
-  [Events.ReloadInspectedPage]: boolean,
-  [Events.RevealSourceLine]: RevealSourceLineEvent,
-  [Events.SavedURL]: SavedURLEvent,
-  [Events.SearchCompleted]: SearchCompletedEvent,
-  [Events.SetInspectedTabId]: string,
-  [Events.SetUseSoftMenu]: boolean,
-  [Events.ShowPanel]: string,
-};
+export interface EventTypes {
+  [Events.AppendedToURL]: Platform.DevToolsPath.RawPathString|Platform.DevToolsPath.UrlString;
+  [Events.CanceledSaveURL]: Platform.DevToolsPath.UrlString;
+  [Events.ColorThemeChanged]: void;
+  [Events.ContextMenuCleared]: void;
+  [Events.ContextMenuItemSelected]: number;
+  [Events.DeviceCountUpdated]: number;
+  [Events.DevicesDiscoveryConfigChanged]: Adb.Config;
+  [Events.DevicesPortForwardingStatusChanged]: void;
+  [Events.DevicesUpdated]: void;
+  [Events.DispatchMessage]: string;
+  [Events.DispatchMessageChunk]: DispatchMessageChunkEvent;
+  [Events.EnterInspectElementMode]: void;
+  [Events.EyeDropperPickedColor]: EyeDropperPickedColorEvent;
+  [Events.FileSystemsLoaded]: DevToolsFileSystem[];
+  [Events.FileSystemRemoved]: Platform.DevToolsPath.RawPathString;
+  [Events.FileSystemAdded]: FileSystemAddedEvent;
+  [Events.FileSystemFilesChangedAddedRemoved]: FilesChangedEvent;
+  [Events.IndexingTotalWorkCalculated]: IndexingTotalWorkCalculatedEvent;
+  [Events.IndexingWorked]: IndexingWorkedEvent;
+  [Events.IndexingDone]: IndexingEvent;
+  [Events.KeyEventUnhandled]: KeyEventUnhandledEvent;
+  [Events.ReloadInspectedPage]: boolean;
+  [Events.RevealSourceLine]: RevealSourceLineEvent;
+  [Events.SavedURL]: SavedURLEvent;
+  [Events.SearchCompleted]: SearchCompletedEvent;
+  [Events.SetInspectedTabId]: string;
+  [Events.SetUseSoftMenu]: boolean;
+  [Events.ShowPanel]: string;
+}
 
 export interface InspectorFrontendHostAPI {
   addFileSystem(type?: string): void;

front_end/core/i18n/i18nTypes.ts

@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export type Values = {
-  [key: string]: string|boolean|number,
-};
+export interface Values {
+  [key: string]: string|boolean|number;
+}
 
 export interface SerializedMessage {
   string: string;

front_end/core/platform/ServerTiming.ts

@@ -29,14 +29,14 @@ const defaultWarningMessages: ServerTimingParsingWarningMessage = {
   },
 };
 
-export type ServerTimingParsingWarningMessage = {
-  deprecratedSyntax: () => string,
-  duplicateParameter: (parameter: string) => string,
-  noValueFoundForParameter: (parameter: string) => string,
-  unrecognizedParameter: (parameter: string) => string,
-  extraneousTrailingCharacters: () => string,
-  unableToParseValue: (parameter: string, value: string) => string,
-};
+export interface ServerTimingParsingWarningMessage {
+  deprecratedSyntax: () => string;
+  duplicateParameter: (parameter: string) => string;
+  noValueFoundForParameter: (parameter: string) => string;
+  unrecognizedParameter: (parameter: string) => string;
+  extraneousTrailingCharacters: () => string;
+  unableToParseValue: (parameter: string, value: string) => string;
+}
 
 export class ServerTiming {
   metric: string;

front_end/core/protocol_client/InspectorBackend.ts

@@ -39,10 +39,10 @@ export const DevToolsStubErrorCode = -32015;
 const GenericErrorCode = -32000;
 const ConnectionClosedErrorCode = -32001;
 
-type MessageParams = {
+interface MessageParams {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  [x: string]: any,
-};
+  [x: string]: any;
+}
 
 type ProtocolDomainName = ProtocolProxyApi.ProtocolDomainName;
 
@@ -52,15 +52,15 @@ export interface MessageError {
   data?: string|null;
 }
 
-export type Message = {
-  sessionId?: string,
-  url?: Platform.DevToolsPath.UrlString,
-  id?: number,
-  error?: MessageError|null,
-  result?: Object|null,
-  method?: QualifiedName,
-  params?: MessageParams|null,
-};
+export interface Message {
+  sessionId?: string;
+  url?: Platform.DevToolsPath.UrlString;
+  id?: number;
+  error?: MessageError|null;
+  result?: Object|null;
+  method?: QualifiedName;
+  params?: MessageParams|null;
+}
 
 interface EventMessage extends Message {
   method: QualifiedName;

front_end/core/sdk/AccessibilityModel.ts

@@ -196,9 +196,9 @@ export const enum Events {
   TREE_UPDATED = 'TreeUpdated',
 }
 
-export type EventTypes = {
-  [Events.TREE_UPDATED]: {root?: AccessibilityNode},
-};
+export interface EventTypes {
+  [Events.TREE_UPDATED]: {root?: AccessibilityNode};
+}
 
 export class AccessibilityModel extends SDKModel<EventTypes> implements ProtocolProxyApi.AccessibilityDispatcher {
   agent: ProtocolProxyApi.AccessibilityApi;