Fix lint findings

__tests__/filter.test.ts

@@ -1,7 +1,7 @@
 import {describe, expect, test} from 'vitest'
 
-import {Filter} from '../src/filter'
 import {File, ChangeStatus} from '../src/file'
+import {Filter} from '../src/filter'
 
 describe('yaml filter parsing tests', () => {
   test('throws if yaml is not a dictionary', () => {
@@ -26,7 +26,7 @@ describe('matching tests', () => {
     const yaml = `
     src: "src/**/*.js"
     `
-    let filter = new Filter(yaml)
+    const filter = new Filter(yaml)
     const files = modified(['src/app/module/file.js'])
     const match = filter.match(files)
     expect(match.src).toEqual(files)

__tests__/git.test.ts

@@ -1,10 +1,10 @@
 import {describe, expect, test} from 'vitest'
 
-import * as git from '../src/git'
 import {ChangeStatus} from '../src/file'
+import * as git from '../src/git'
 
 describe('parsing output of the git diff command', () => {
-  test('parseGitDiffOutput returns files with correct change status', async () => {
+  test('parseGitDiffOutput returns files with correct change status', () => {
     const files = git.parseGitDiffOutput(
       'A\u0000LICENSE\u0000' + 'M\u0000src/index.ts\u0000' + 'D\u0000src/main.ts\u0000'
     )

src/exec.ts

@@ -3,12 +3,12 @@ import {exec as execImpl, ExecOptions} from '@actions/exec'
 // Wraps original exec() function
 // Returns exit code and whole stdout/stderr
 export default async function exec(commandLine: string, args?: string[], options?: ExecOptions): Promise<ExecResult> {
-  options = options || {}
+  options = options ?? {}
   let stdout = ''
   let stderr = ''
   options.listeners = {
-    stdout: (data: Buffer) => (stdout += data.toString()),
-    stderr: (data: Buffer) => (stderr += data.toString())
+    stdout: (data: Buffer): string => (stdout += data.toString()),
+    stderr: (data: Buffer): string => (stderr += data.toString())
   }
   const code = await execImpl(commandLine, args, options)
   return {code, stdout, stderr}

src/filter.ts

@@ -1,11 +1,10 @@
 import * as jsyaml from 'js-yaml'
 import micromatch from 'micromatch'
+
 import {File} from './file'
 
 // Type definition of object we expect to load from YAML
-interface FilterYaml {
-  [name: string]: FilterItemYaml
-}
+type FilterYaml = Record<string, FilterItemYaml>
 type FilterItemYaml =
   | string // Filename pattern, e.g. "path/to/*.js"
   | FilterItemYaml[] // Supports referencing another rule via YAML anchor
@@ -15,12 +14,10 @@ const MatchOptions: micromatch.Options = {
   dot: true
 }
 
-export interface FilterResults {
-  [key: string]: File[]
-}
+export type FilterResults = Partial<Record<string, File[]>>
 
 export class Filter {
-  rules: {[key: string]: string[]} = {}
+  rules: Record<string, string[]> = {}
 
   // Creates instance of Filter and load rules from YAML if it's provided
   constructor(yaml?: string) {
@@ -47,9 +44,9 @@ export class Filter {
 
   match(files: File[]): FilterResults {
     const result: FilterResults = {}
-    const filesMap = files.reduce((result, x) => {
-      result.set(x.filename, x)
-      return result
+    const filesMap = files.reduce((fileResult, x) => {
+      fileResult.set(x.filename, x)
+      return fileResult
     }, new Map<string, File>())
 
     for (const [key, patterns] of Object.entries(this.rules)) {

src/git.ts

@@ -1,5 +1,6 @@
-import exec from './exec'
 import * as core from '@actions/core'
+
+import exec from './exec'
 import {File, ChangeStatus} from './file'
 
 export const NULL_SHA = '0000000000000000000000000000000000000000'
@@ -215,7 +216,7 @@ async function getLocalRef(shortName: string): Promise<string | undefined> {
   const output = (await exec('git', ['show-ref', shortName], {ignoreReturnCode: true})).stdout
   const refs = output
     .split(/\r?\n/g)
-    .map(l => l.match(/refs\/(?:(?:heads)|(?:tags)|(?:remotes\/origin))\/(.*)$/))
+    .map(l => /refs\/(?:(?:heads)|(?:tags)|(?:remotes\/origin))\/(.*)$/.exec(l))
     .filter(match => match !== null && match[1] === shortName)
     .map(match => match?.[0] ?? '') // match can't be null here but compiler doesn't understand that
 
@@ -260,7 +261,7 @@ function fixStdOutNullTermination(): void {
   core.info('')
 }
 
-const statusMap: {[char: string]: ChangeStatus} = {
+const statusMap: Record<string, ChangeStatus> = {
   A: ChangeStatus.Added,
   C: ChangeStatus.Copied,
   D: ChangeStatus.Deleted,

src/main.ts

@@ -1,13 +1,14 @@
-import * as fs from 'fs'
+import * as fs from 'node:fs'
+
 import * as core from '@actions/core'
 import * as github from '@actions/github'
 import {PullRequest, PushEvent} from '@octokit/webhooks-types'
 
-import {Filter, FilterResults} from './filter'
 import {File, ChangeStatus} from './file'
+import {Filter, FilterResults} from './filter'
 import * as git from './git'
-import {backslashEscape, shellEscape} from './list-format/shell-escape'
 import {csvEscape} from './list-format/csv-escape'
+import {backslashEscape, shellEscape} from './list-format/shell-escape'
 
 type ExportFormat = 'none' | 'csv' | 'json' | 'shell' | 'escape'
 
@@ -95,7 +96,10 @@ async function getChangedFiles(token: string, base: string, ref: string, initial
 }
 
 async function getChangedFilesFromGit(base: string, head: string, initialFetchDepth: number): Promise<File[]> {
-  const defaultBranch = github.context.payload.repository?.default_branch
+  const defaultBranch =
+    typeof github.context.payload.repository?.default_branch === 'string'
+      ? github.context.payload.repository.default_branch
+      : ''
 
   const beforeSha = github.context.eventName === 'push' ? (github.context.payload as PushEvent).before : null
 
@@ -174,6 +178,7 @@ async function getChangedFilesFromApi(token: string, prNumber: PullRequest): Pro
         page
       })
 
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
       if (response.status !== 200) {
         throw new Error(`Fetching list of changed files from GitHub API failed with error code ${response.status}`)
       }
@@ -195,8 +200,9 @@ async function getChangedFilesFromApi(token: string, prNumber: PullRequest): Pro
             status: ChangeStatus.Added
           })
           files.push({
-            // 'previous_filename' for some unknown reason isn't in the type definition or documentation
-            filename: (<any>row).previous_filename as string,
+            // Existing behaviour, possibly a bug
+            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+            filename: row.previous_filename!,
             status: ChangeStatus.Deleted
           })
         } else {
@@ -220,6 +226,8 @@ function exportResults(results: FilterResults, format: ExportFormat): void {
   core.info('Results:')
   const changes = []
   for (const [key, files] of Object.entries(results)) {
+    if (!files) continue
+
     const value = files.length > 0
     core.startGroup(`Filter ${key} = ${value}`)
     if (files.length > 0) {
@@ -241,7 +249,7 @@ function exportResults(results: FilterResults, format: ExportFormat): void {
     core.endGroup()
   }
 
-  if (results['changes'] === undefined) {
+  if (results.changes === undefined) {
     const changesJson = JSON.stringify(changes)
     core.info(`Changes output set to ${changesJson}`)
     core.setOutput('changes', changesJson)
@@ -270,4 +278,4 @@ function isExportFormat(value: string): value is ExportFormat {
   return ['none', 'csv', 'shell', 'json', 'escape'].includes(value)
 }
 
-run()
+;((): Promise<void> => run())()