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GitHub actions to get git diff.

1. Example workflow
   
2. Skip
   

on: pull_request
name: CI
jobs:
  eslint:
    name: ESLint
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: technote-space/get-diff-action@v1
        with:
          PREFIX_FILTER: |
            src
            __tests__
          SUFFIX_FILTER: .ts
      - name: Install Package dependencies
        run: yarn install
        if: env.GIT_DIFF
      - name: Check code style
        # Check only the source codes that have differences
        run: yarn eslint ${{ env.GIT_DIFF }}
        if: env.GIT_DIFF

If there is no difference in the source code below, this workflow will skip the code style check

• src/**/*.ts
• __tests__/**/*.ts

1. Get git diff

   git diff "${FROM}"${DOT}"${TO}" '--diff-filter=${DIFF_FILTER}' --name-only

   e.g. (default)

   FROM: 'origin/${GITHUB_BASE_REF}'
   TO: '${GITHUB_REF#refs/}'
   DOT: '...'
   DIFF_FILTER: 'AM'

   =>

   git diff "origin/${GITHUB_BASE_REF}"..."${GITHUB_REF#refs/}" '--diff-filter=AM' --name-only

   =>

   .github/workflows/ci.yml
   __tests__/utils/command.test.ts
   package.json
   src/main.ts
   src/utils/command.ts
   yarn.lock
   

2. Filtered by PREFIX_FILTER or SUFFIX_FILTER option

   e.g.

   SUFFIX_FILTER: .ts
   PREFIX_FILTER: src/

   =>

   src/main.ts
   src/utils/command.ts
   

3. Mapped to absolute if ABSOLUTE option is true(default)

   e.g. (default)

   /home/runner/work/my-repo-name/my-repo-name/src/main.ts
   /home/runner/work/my-repo-name/my-repo-name/src/utils/command.ts
   

4. Combined by SEPARATOR option

   e.g.

   SEPARATOR: ' '

   =>

   /home/runner/work/my-repo-name/my-repo-name/src/main.ts /home/runner/work/my-repo-name/my-repo-name/src/utils/command.ts
   

The results of diff file names.
if inputs SET_ENV_NAME is set, an environment variable is set with that name.
default: SET_ENV_NAME=GIT_DIFF

The number of diff files.
if inputs SET_ENV_NAME_COUNT is set, an environment variable is set with that name.
default: SET_ENV_NAME_COUNT=

The number of insertions lines.
if inputs SET_ENV_NAME_INSERTIONS is set, an environment variable is set with that name.
default: SET_ENV_NAME_INSERTIONS=

The number of deletions lines.
if inputs SET_ENV_NAME_DELETIONS is set, an environment variable is set with that name.
default: SET_ENV_NAME_DELETIONS=

The number of diff lines.
if inputs SET_ENV_NAME_LINES is set, an environment variable is set with that name.
default: SET_ENV_NAME_LINES=

If called on any other event, the result will be empty.

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