fix: remove @types/eslint dependency as eslint is optional

✅ Closes: #379

package.json

@@ -85,7 +85,6 @@
   "devDependencies": {
     "@commitlint/config-conventional": "^7.5.0",
     "@types/babel-code-frame": "^6.20.1",
-    "@types/eslint": "^4.16.6",
     "@types/jest": "^24.0.11",
     "@types/lodash": "^4.14.134",
     "@types/micromatch": "^3.1.0",

src/ApiIncrementalChecker.ts

@@ -1,5 +1,3 @@
-import * as eslint from 'eslint'; // Imported for types alone
-
 import {
   IncrementalCheckerInterface,
   IncrementalCheckerParams
@@ -11,11 +9,12 @@ import {
   createIssuesFromTsDiagnostics,
   createIssuesFromEsLintReports
 } from './issue';
+import { LintReport } from './types/eslint';
 
 export class ApiIncrementalChecker implements IncrementalCheckerInterface {
   protected readonly tsIncrementalCompiler: CompilerHost;
 
-  private currentEsLintErrors = new Map<string, eslint.CLIEngine.LintReport>();
+  private currentEsLintErrors = new Map<string, LintReport>();
   private lastUpdatedFiles: string[] = [];
   private lastRemovedFiles: string[] = [];
 

src/FilesRegister.ts

@@ -1,10 +1,10 @@
 import * as ts from 'typescript'; // import for types alone
-import * as eslint from 'eslint'; // import for types alone
+import { LintReport } from './types/eslint';
 
 export interface DataShape {
   source?: ts.SourceFile;
   linted: boolean;
-  eslints: eslint.CLIEngine.LintReport[];
+  eslints: LintReport[];
 }
 
 export class FilesRegister {

src/IncrementalChecker.ts

@@ -1,7 +1,6 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import * as ts from 'typescript'; // Imported for types alone; actual requires take place in methods below
-import * as eslint from 'eslint';
 
 import { FilesRegister } from './FilesRegister';
 import { CancellationToken } from './CancellationToken';
@@ -22,6 +21,7 @@ import {
   createIssuesFromEsLintReports,
   createIssuesFromTsDiagnostics
 } from './issue';
+import { LintReport } from './types/eslint';
 
 export class IncrementalChecker implements IncrementalCheckerInterface {
   private files = new FilesRegister(() => ({
@@ -261,7 +261,7 @@ export class IncrementalChecker implements IncrementalCheckerInterface {
           !IncrementalChecker.isFileExcluded(filePath)
       );
 
-    const currentEsLintErrors = new Map<string, eslint.CLIEngine.LintReport>();
+    const currentEsLintErrors = new Map<string, LintReport>();
     filesToLint.forEach(fileName => {
       cancellationToken.throwIfCancellationRequested();
 
@@ -289,7 +289,7 @@ export class IncrementalChecker implements IncrementalCheckerInterface {
 
     const reports = this.files
       .keys()
-      .reduce<eslint.CLIEngine.LintReport[]>(
+      .reduce<LintReport[]>(
         (innerLints, filePath) =>
           innerLints.concat(this.files.getData(filePath).eslints),
         []

src/createEslinter.ts

@@ -1,16 +1,16 @@
-import * as eslint from 'eslint'; // import for types alone
 import * as path from 'path';
 
+import { LintReport } from './types/eslint';
 import { throwIfIsInvalidSourceFileError } from './FsHelper';
 
 export function createEslinter(eslintOptions: object) {
   // eslint-disable-next-line @typescript-eslint/no-var-requires
-  const { CLIEngine }: typeof eslint = require('eslint');
+  const { CLIEngine } = require('eslint');
 
   // See https://eslint.org/docs/1.0.0/developer-guide/nodejs-api#cliengine
   const eslinter = new CLIEngine(eslintOptions);
 
-  function getReport(filepath: string) {
+  function getReport(filepath: string): LintReport | undefined {
     try {
       if (
         eslinter.isPathIgnored(filepath) ||

src/issue/eslint/EsLintIssueFactory.ts

@@ -1,8 +1,8 @@
-import * as eslint from 'eslint';
 import { FileAwareEsLintMessage } from './FileAwareEsLintMessage';
 import { deduplicateAndSortIssues, Issue } from '../Issue';
 import { IssueOrigin } from '../IssueOrigin';
 import { IssueSeverity } from '../IssueSeverity';
+import { LintReport, LintResult } from '../../types/eslint';
 
 function createIssueFromEsLintMessage(message: FileAwareEsLintMessage): Issue {
   return {
@@ -18,7 +18,7 @@ function createIssueFromEsLintMessage(message: FileAwareEsLintMessage): Issue {
 }
 
 function createFileAwareEsLintMessagesFromEsLintResult(
-  result: eslint.CLIEngine.LintResult
+  result: LintResult
 ): FileAwareEsLintMessage[] {
   return result.messages.map(message => ({
     ...message,
@@ -27,7 +27,7 @@ function createFileAwareEsLintMessagesFromEsLintResult(
 }
 
 function createFileAwareEsLintMessagesFromEsLintReport(
-  report: eslint.CLIEngine.LintReport
+  report: LintReport
 ): FileAwareEsLintMessage[] {
   return report.results.reduce<FileAwareEsLintMessage[]>(
     (messages, result) => [
@@ -39,7 +39,7 @@ function createFileAwareEsLintMessagesFromEsLintReport(
 }
 
 function createFileAwareEsLintMessagesFromEsLintReports(
-  reports: eslint.CLIEngine.LintReport[]
+  reports: LintReport[]
 ): FileAwareEsLintMessage[] {
   return reports.reduce<FileAwareEsLintMessage[]>(
     (messages, report) => [
@@ -56,9 +56,7 @@ function createIssuesFromEsLintMessages(
   return deduplicateAndSortIssues(messages.map(createIssueFromEsLintMessage));
 }
 
-function createIssuesFromEsLintReports(
-  reports: eslint.CLIEngine.LintReport[]
-): Issue[] {
+function createIssuesFromEsLintReports(reports: LintReport[]): Issue[] {
   return createIssuesFromEsLintMessages(
     createFileAwareEsLintMessagesFromEsLintReports(reports)
   );

src/issue/eslint/FileAwareEsLintMessage.ts

@@ -1,10 +1,10 @@
-import * as eslint from 'eslint';
+import { LintMessage } from '../../types/eslint';
 
 /**
  * We need to define custom interface because of eslint architecture which
  * groups lint messages per file
  */
-interface FileAwareEsLintMessage extends eslint.Linter.LintMessage {
+interface FileAwareEsLintMessage extends LintMessage {
   filePath?: string;
 }
 

src/types/eslint.ts

@@ -0,0 +1,36 @@
+// copy eslint types as installation of eslint package is optional
+export interface LintMessage {
+  column: number;
+  line: number;
+  endColumn?: number;
+  endLine?: number;
+  ruleId: string | null;
+  message: string;
+  nodeType: string;
+  fatal?: true;
+  severity: 0 | 1 | 2;
+  fix?: {
+    range: [number, number];
+    text: string;
+  };
+  source: string | null;
+}
+
+export interface LintResult {
+  filePath: string;
+  messages: LintMessage[];
+  errorCount: number;
+  warningCount: number;
+  fixableErrorCount: number;
+  fixableWarningCount: number;
+  output?: string;
+  source?: string;
+}
+
+export interface LintReport {
+  results: LintResult[];
+  errorCount: number;
+  warningCount: number;
+  fixableErrorCount: number;
+  fixableWarningCount: number;
+}

test/unit/issue/eslint/EsLintIssueFactory.spec.ts

@@ -1,11 +1,11 @@
 import { createIssuesFromEsLintReports } from '../../../../lib/issue';
-import * as eslint from 'eslint';
+import {
+  LintMessage,
+  LintReport,
+  LintResult
+} from '../../../../lib/types/eslint';
 
 describe('[UNIT] issue/eslint/EsLintIssueFactory', () => {
-  type LintMessage = eslint.Linter.LintMessage;
-  type LintResult = eslint.CLIEngine.LintResult;
-  type LintReport = eslint.CLIEngine.LintReport;
-
   const ES_LINT_MESSAGE_ERROR: LintMessage = {
     column: 0,
     line: 13,

yarn.lock

@@ -490,19 +490,6 @@
   resolved "https://registry.yarnpkg.com/@types/eslint-visitor-keys/-/eslint-visitor-keys-1.0.0.tgz#1ee30d79544ca84d68d4b3cdb0af4f205663dd2d"
   integrity sha512-OCutwjDZ4aFS6PB1UZ988C4YgwlBHJd6wCeQqaLdmadZ/7e+w79+hbMUFC1QXDNCmdyoRfAFdm0RypzwR+Qpag==
 
-"@types/eslint@^4.16.6":
-  version "4.16.6"
-  resolved "https://registry.yarnpkg.com/@types/eslint/-/eslint-4.16.6.tgz#96d4ecddbea618ab0b55eaf0dffedf387129b06c"
-  integrity sha512-GL7tGJig55FeclpOytU7nCCqtR143jBoC7AUdH0DO9xBSIFiNNUFCY/S3KNWsHeQJuU3hjw/OC1+kRTFNXqUZQ==
-  dependencies:
-    "@types/estree" "*"
-    "@types/json-schema" "*"
-
-"@types/estree@*":
-  version "0.0.39"
-  resolved "https://registry.yarnpkg.com/@types/estree/-/estree-0.0.39.tgz#e177e699ee1b8c22d23174caaa7422644389509f"
-  integrity sha512-EYNwp3bU+98cpU4lAWYYL7Zz+2gryWH1qbdDTidVd6hkiR6weksdbMadyXKXNPEkQFhXM+hVO9ZygomHXp+AIw==
-
 "@types/events@*":
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/@types/events/-/events-1.2.0.tgz#81a6731ce4df43619e5c8c945383b3e62a89ea86"
@@ -533,7 +520,7 @@
   dependencies:
     "@types/jest-diff" "*"
 
-"@types/json-schema@*", "@types/json-schema@^7.0.3":
+"@types/json-schema@^7.0.3":
   version "7.0.3"
   resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.3.tgz#bdfd69d61e464dcc81b25159c270d75a73c1a636"
   integrity sha512-Il2DtDVRGDcqjDtE+rF8iqg1CArehSK84HZJCT7AMITlyXRBpuPhqGLDQMowraqqu1coEaimg4ZOqggt6L6L+A==