Improve change detection for feature branches (#16)

* Detect changes against configured base branch * Update README and action.yml * Add job.outputs example * Update CHANGELOG
dorny · Jun 24, 2020 · 83deb9f · 83deb9f
1 parent 7d20182
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## v2.2.0
+- [Improve change detection for feature branches](https://github.com/dorny/paths-filter/pull/16)
+
 ## v2.1.0
 - [Support reusable paths blocks with yaml anchors](https://github.com/dorny/paths-filter/pull/13)
 

diff --git a/README.md b/README.md
@@ -10,9 +10,12 @@ It saves time and resources especially in monorepo setups, where you can run slo
 Github workflows built-in [path filters](https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestpaths)
 doesn't allow this because they doesn't work on a level of individual jobs or steps.
 
-Action supports workflows triggered by:
-- **[pull_request](https://help.github.com/en/actions/reference/events-that-trigger-workflows#pull-request-event-pull_request)**: changes are detected against the base branch
-- **[push](https://help.github.com/en/actions/reference/events-that-trigger-workflows#push-event-push)**: changes are detected against the most recent commit on the same branch before the push
+Supported workflows:
+- Action triggered by **[pull_request](https://help.github.com/en/actions/reference/events-that-trigger-workflows#pull-request-event-pull_request)** event:
+  - changes detected against the pull request base branch
+- Action triggered by **[push](https://help.github.com/en/actions/reference/events-that-trigger-workflows#push-event-push)** event:
+  - changes detected against the most recent commit on the same branch before the push
+  - changes detected against the top of the configured *base* branch (e.g. master)
 
 ## Usage
 
@@ -22,7 +25,10 @@ Corresponding output variable will be created to indicate if there's a changed f
 Output variables can be later used in the `if` clause to conditionally run specific steps.
 
 ### Inputs
-- **`token`**: GitHub Access Token - defaults to `${{ github.token }}`
+- **`token`**: GitHub Access Token - defaults to `${{ github.token }}` so you don't have to explicitly provide it.
+- **`base`**: Git reference (e.g. branch name) against which the changes will be detected. Defaults to repository default branch (e.g. master).
+              If it references same branch it was pushed to, changes are detected against the most recent commit before the push.
+              This option is ignored if action is triggered by *pull_request* event.
 - **`filters`**: Path to the configuration file or directly embedded string in YAML format. Filter configuration is a dictionary, where keys specifies rule names and values are lists of file path patterns.
 
 ### Outputs
@@ -34,6 +40,8 @@ Output variables can be later used in the `if` clause to conditionally run speci
 - minimatch [dot](https://www.npmjs.com/package/minimatch#dot) option is set to true - therefore
   globbing will match also paths where file or folder name starts with a dot.
 - You can use YAML anchors to reuse path expression(s) inside another rule. See example in the tests.
+- If changes are detected against the previous commit and there is none (i.e. first push of a new branch), all filter rules will report changed files.
+- You can use `base: ${{ github.ref }}` to configure change detection against previous commit for every branch you create.
 
 ### Example
 ```yaml
@@ -49,7 +57,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: dorny/paths-filter@v2.1.0
+    - uses: dorny/paths-filter@v2.2.0
       id: filter
       with:
         # inline YAML or path to separate file (e.g.: .github/filters.yaml)
@@ -75,13 +83,47 @@ jobs:
       run: ...
 ```
 
+If your workflow uses multiple jobs, you can put *paths-filter* into own job and use
+[job outputs](https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjobs_idoutputs)
+in other jobs [if](https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjob_idif) statements:
+```yml
+on:
+  pull_request:
+    branches:
+      - master
+jobs:
+  changes:
+    runs-on: ubuntu-latest
+    # Set job outputs to values from filter step
+    outputs:
+      backend: ${{ steps.filter.outputs.backend }}
+      frontend: ${{ steps.filter.outputs.frontend }}
+    steps:
+    # For pull requests it's not necessary to checkout the code
+    - uses: dorny/paths-filter@v2.2.0
+      id: filter
+      with:
+        # Filters stored in own yaml file
+        filters: '.github/filters.yml'
+  backend:
+    if: ${{ needs.changes.outputs.backend == 'true' }}
+    steps:
+      - ...
+  frontend:
+    if: ${{ needs.changes.outputs.frontend == 'true' }}
+    steps:
+      - ...
+```
+
 ## How it works
 
 1. If action was triggered by pull request:
    - If access token was provided it's used to fetch list of changed files from Github API.
-   - If access token was not provided, top of the base branch is fetched and changed files are detected using `git diff-index` command.
+   - If access token was not provided, top of the base branch is fetched and changed files are detected using `git diff-index <SHA>` command.
 2. If action was triggered by push event
-   - Last commit before the push is fetched and changed files are detected using `git diff-index` command.
+   - if *base* input parameter references same branch it was pushed to, most recent commit before the push is fetched
+   - If *base* input parameter references other branch, top of that branch is fetched
+   - changed files are detected using `git diff-index FETCH_HEAD` command.
 3. For each filter rule it checks if there is any matching file
 4. Output variables are set
 

diff --git a/__tests__/main.test.ts → __tests__/filter.test.ts b/__tests__/main.test.ts → __tests__/filter.test.ts
diff --git a/__tests__/git.test.ts b/__tests__/git.test.ts
@@ -0,0 +1,19 @@
+import * as git from '../src/git'
+
+describe('git utility function tests (those not invoking git)', () => {
+  test('Detects if ref references a tag', () => {
+    expect(git.isTagRef('refs/tags/v1.0')).toBeTruthy()
+    expect(git.isTagRef('refs/heads/master')).toBeFalsy()
+    expect(git.isTagRef('master')).toBeFalsy()
+  })
+  test('Trims "refs/" from ref', () => {
+    expect(git.trimRefs('refs/heads/master')).toBe('heads/master')
+    expect(git.trimRefs('heads/master')).toBe('heads/master')
+    expect(git.trimRefs('master')).toBe('master')
+  })
+  test('Trims "refs/" and "heads/" from ref', () => {
+    expect(git.trimRefsHeads('refs/heads/master')).toBe('master')
+    expect(git.trimRefsHeads('heads/master')).toBe('master')
+    expect(git.trimRefsHeads('master')).toBe('master')
+  })
+})
diff --git a/action.yml b/action.yml
@@ -6,6 +6,12 @@ inputs:
     description: 'GitHub Access Token'
     required: false
     default: ${{ github.token }}
+  base:
+    description: |
+      Git reference (e.g. branch name) against which the changes will be detected. Defaults to repository default branch (e.g. master).
+      If it references same branch it was pushed to, changes are detected against the most recent commit before the push.
+      This option is ignored if action is triggered by pull_request event.
+    required: false
   filters:
     description: 'Path to the configuration file or YAML string with filters definition'
     required: true

diff --git a/dist/index.js b/dist/index.js
@@ -3798,21 +3798,23 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
     });
 };
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.getChangedFiles = exports.fetchCommit = void 0;
+exports.trimRefsHeads = exports.trimRefs = exports.isTagRef = exports.getChangedFiles = exports.fetchCommit = exports.FETCH_HEAD = exports.NULL_SHA = void 0;
 const exec_1 = __webpack_require__(986);
-function fetchCommit(sha) {
+exports.NULL_SHA = '0000000000000000000000000000000000000000';
+exports.FETCH_HEAD = 'FETCH_HEAD';
+function fetchCommit(ref) {
     return __awaiter(this, void 0, void 0, function* () {
-        const exitCode = yield exec_1.exec('git', ['fetch', '--depth=1', 'origin', sha]);
+        const exitCode = yield exec_1.exec('git', ['fetch', '--depth=1', '--no-tags', 'origin', ref]);
         if (exitCode !== 0) {
-            throw new Error(`Fetching commit ${sha} failed`);
+            throw new Error(`Fetching ${ref} failed`);
         }
     });
 }
 exports.fetchCommit = fetchCommit;
-function getChangedFiles(sha) {
+function getChangedFiles(ref) {
     return __awaiter(this, void 0, void 0, function* () {
         let output = '';
-        const exitCode = yield exec_1.exec('git', ['diff-index', '--name-only', sha], {
+        const exitCode = yield exec_1.exec('git', ['diff-index', '--name-only', ref], {
             listeners: {
                 stdout: (data) => (output += data.toString())
             }
@@ -3827,6 +3829,22 @@ function getChangedFiles(sha) {
     });
 }
 exports.getChangedFiles = getChangedFiles;
+function isTagRef(ref) {
+    return ref.startsWith('refs/tags/');
+}
+exports.isTagRef = isTagRef;
+function trimRefs(ref) {
+    return trimStart(ref, 'refs/');
+}
+exports.trimRefs = trimRefs;
+function trimRefsHeads(ref) {
+    const trimRef = trimStart(ref, 'refs/');
+    return trimStart(trimRef, 'heads/');
+}
+exports.trimRefsHeads = trimRefsHeads;
+function trimStart(ref, start) {
+    return ref.startsWith(start) ? ref.substr(start.length) : ref;
+}
 
 
 /***/ }),
@@ -4487,9 +4505,18 @@ function run() {
             const filtersYaml = isPathInput(filtersInput) ? getConfigFileContent(filtersInput) : filtersInput;
             const filter = new filter_1.default(filtersYaml);
             const files = yield getChangedFiles(token);
-            const result = filter.match(files);
-            for (const key in result) {
-                core.setOutput(key, String(result[key]));
+            if (files === null) {
+                // Change detection was not possible
+                // Set all filter keys to true (i.e. changed)
+                for (const key in filter.rules) {
+                    core.setOutput(key, String(true));
+                }
+            }
+            else {
+                const result = filter.match(files);
+                for (const key in result) {
+                    core.setOutput(key, String(result[key]));
+                }
             }
         }
         catch (error) {
@@ -4516,20 +4543,40 @@ function getChangedFiles(token) {
             return token ? yield getChangedFilesFromApi(token, pr) : yield getChangedFilesFromGit(pr.base.sha);
         }
         else if (github.context.eventName === 'push') {
-            const push = github.context.payload;
-            return yield getChangedFilesFromGit(push.before);
+            return getChangedFilesFromPush();
         }
         else {
             throw new Error('This action can be triggered only by pull_request or push event');
         }
     });
 }
+function getChangedFilesFromPush() {
+    return __awaiter(this, void 0, void 0, function* () {
+        const push = github.context.payload;
+        // No change detection for pushed tags
+        if (git.isTagRef(push.ref))
+            return null;
+        // Get base from input or use repo default branch.
+        // It it starts with 'refs/', it will be trimmed (git fetch refs/heads/<NAME> doesn't work)
+        const baseInput = git.trimRefs(core.getInput('base', { required: false }) || push.repository.default_branch);
+        // If base references same branch it was pushed to, we will do comparison against the previously pushed commit.
+        // Otherwise changes are detected against the base reference
+        const base = git.trimRefsHeads(baseInput) === git.trimRefsHeads(push.ref) ? push.before : baseInput;
+        // There is no previous commit for comparison
+        // e.g. change detection against previous commit of just pushed new branch
+        if (base === git.NULL_SHA)
+            return null;
+        return yield getChangedFilesFromGit(base);
+    });
+}
 // Fetch base branch and use `git diff` to determine changed files
-function getChangedFilesFromGit(sha) {
+function getChangedFilesFromGit(ref) {
     return __awaiter(this, void 0, void 0, function* () {
         core.debug('Fetching base branch and using `git diff-index` to determine changed files');
-        yield git.fetchCommit(sha);
-        return yield git.getChangedFiles(sha);
+        yield git.fetchCommit(ref);
+        // FETCH_HEAD will always point to the just fetched commit
+        // No matter if ref is SHA, branch or tag name or full git ref
+        return yield git.getChangedFiles(git.FETCH_HEAD);
     });
 }
 // Uses github REST api to get list of files changed in PR

diff --git a/src/git.ts b/src/git.ts
@@ -1,15 +1,18 @@
 import {exec} from '@actions/exec'
 
-export async function fetchCommit(sha: string): Promise<void> {
-  const exitCode = await exec('git', ['fetch', '--depth=1', 'origin', sha])
+export const NULL_SHA = '0000000000000000000000000000000000000000'
+export const FETCH_HEAD = 'FETCH_HEAD'
+
+export async function fetchCommit(ref: string): Promise<void> {
+  const exitCode = await exec('git', ['fetch', '--depth=1', '--no-tags', 'origin', ref])
   if (exitCode !== 0) {
-    throw new Error(`Fetching commit ${sha} failed`)
+    throw new Error(`Fetching ${ref} failed`)
   }
 }
 
-export async function getChangedFiles(sha: string): Promise<string[]> {
+export async function getChangedFiles(ref: string): Promise<string[]> {
   let output = ''
-  const exitCode = await exec('git', ['diff-index', '--name-only', sha], {
+  const exitCode = await exec('git', ['diff-index', '--name-only', ref], {
     listeners: {
       stdout: (data: Buffer) => (output += data.toString())
     }
@@ -24,3 +27,20 @@ export async function getChangedFiles(sha: string): Promise<string[]> {
     .map(s => s.trim())
     .filter(s => s.length > 0)
 }
+
+export function isTagRef(ref: string): boolean {
+  return ref.startsWith('refs/tags/')
+}
+
+export function trimRefs(ref: string): string {
+  return trimStart(ref, 'refs/')
+}
+
+export function trimRefsHeads(ref: string): string {
+  const trimRef = trimStart(ref, 'refs/')
+  return trimStart(trimRef, 'heads/')
+}
+
+function trimStart(ref: string, start: string): string {
+  return ref.startsWith(start) ? ref.substr(start.length) : ref
+}
diff --git a/src/main.ts b/src/main.ts
@@ -15,9 +15,17 @@ async function run(): Promise<void> {
     const filter = new Filter(filtersYaml)
     const files = await getChangedFiles(token)
 
-    const result = filter.match(files)
-    for (const key in result) {
-      core.setOutput(key, String(result[key]))
+    if (files === null) {
+      // Change detection was not possible
+      // Set all filter keys to true (i.e. changed)
+      for (const key in filter.rules) {
+        core.setOutput(key, String(true))
+      }
+    } else {
+      const result = filter.match(files)
+      for (const key in result) {
+        core.setOutput(key, String(result[key]))
+      }
     }
   } catch (error) {
     core.setFailed(error.message)
@@ -40,23 +48,45 @@ function getConfigFileContent(configPath: string): string {
   return fs.readFileSync(configPath, {encoding: 'utf8'})
 }
 
-async function getChangedFiles(token: string): Promise<string[]> {
+async function getChangedFiles(token: string): Promise<string[] | null> {
   if (github.context.eventName === 'pull_request') {
     const pr = github.context.payload.pull_request as Webhooks.WebhookPayloadPullRequestPullRequest
     return token ? await getChangedFilesFromApi(token, pr) : await getChangedFilesFromGit(pr.base.sha)
   } else if (github.context.eventName === 'push') {
-    const push = github.context.payload as Webhooks.WebhookPayloadPush
-    return await getChangedFilesFromGit(push.before)
+    return getChangedFilesFromPush()
   } else {
     throw new Error('This action can be triggered only by pull_request or push event')
   }
 }
 
+async function getChangedFilesFromPush(): Promise<string[] | null> {
+  const push = github.context.payload as Webhooks.WebhookPayloadPush
+
+  // No change detection for pushed tags
+  if (git.isTagRef(push.ref)) return null
+
+  // Get base from input or use repo default branch.
+  // It it starts with 'refs/', it will be trimmed (git fetch refs/heads/<NAME> doesn't work)
+  const baseInput = git.trimRefs(core.getInput('base', {required: false}) || push.repository.default_branch)
+
+  // If base references same branch it was pushed to, we will do comparison against the previously pushed commit.
+  // Otherwise changes are detected against the base reference
+  const base = git.trimRefsHeads(baseInput) === git.trimRefsHeads(push.ref) ? push.before : baseInput
+
+  // There is no previous commit for comparison
+  // e.g. change detection against previous commit of just pushed new branch
+  if (base === git.NULL_SHA) return null
+
+  return await getChangedFilesFromGit(base)
+}
+
 // Fetch base branch and use `git diff` to determine changed files
-async function getChangedFilesFromGit(sha: string): Promise<string[]> {
+async function getChangedFilesFromGit(ref: string): Promise<string[]> {
   core.debug('Fetching base branch and using `git diff-index` to determine changed files')
-  await git.fetchCommit(sha)
-  return await git.getChangedFiles(sha)
+  await git.fetchCommit(ref)
+  // FETCH_HEAD will always point to the just fetched commit
+  // No matter if ref is SHA, branch or tag name or full git ref
+  return await git.getChangedFiles(git.FETCH_HEAD)
 }
 
 // Uses github REST api to get list of files changed in PR