d4e00ee5a1
Moves the merge script from the components repository over to the shared dev-infra package. The merge script has been orginally built for all Angular repositories, but we just kept it in the components repo temporarily to test it. Since everything went well on the components side, we now move the script over and integrate it into the dev-infra package. PR Close #37184
74 lines
3.8 KiB
TypeScript
74 lines
3.8 KiB
TypeScript
import {join} from 'path';
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import {PullRequestFailure} from '../failures';
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import {PullRequest} from '../pull-request';
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import {MergeStrategy, TEMP_PR_HEAD_BRANCH} from './strategy';
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/** Path to the commit message filter script. Git expects this paths to use forward slashes. */
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const MSG_FILTER_SCRIPT = join(__dirname, './commit-message-filter.js').replace(/\\/g, '/');
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/**
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* Merge strategy that does not use the Github API for merging. Instead, it fetches
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* all target branches and the PR locally. The PR is then cherry-picked with autosquash
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* enabled into the target branches. The benefit is the support for fixup and squash commits.
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* A notable downside though is that Github does not show the PR as `Merged` due to non
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* fast-forward merges
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*/
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export class AutosquashMergeStrategy extends MergeStrategy {
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/**
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* Merges the specified pull request into the target branches and pushes the target
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* branches upstream. This method requires the temporary target branches to be fetched
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* already as we don't want to fetch the target branches per pull request merge. This
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* would causes unnecessary multiple fetch requests when multiple PRs are merged.
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* @throws {GitCommandError} An unknown Git command error occurred that is not
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* specific to the pull request merge.
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* @returns A pull request failure or null in case of success.
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*/
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async merge(pullRequest: PullRequest): Promise<PullRequestFailure|null> {
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const {prNumber, targetBranches, requiredBaseSha, needsCommitMessageFixup} = pullRequest;
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// In case a required base is specified for this pull request, check if the pull
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// request contains the given commit. If not, return a pull request failure. This
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// check is useful for enforcing that PRs are rebased on top of a given commit. e.g.
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// a commit that changes the codeowner ship validation. PRs which are not rebased
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// could bypass new codeowner ship rules.
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if (requiredBaseSha && !this.git.hasCommit(TEMP_PR_HEAD_BRANCH, requiredBaseSha)) {
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return PullRequestFailure.unsatisfiedBaseSha();
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}
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// Git revision range that matches the pull request commits.
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const revisionRange = this.getPullRequestRevisionRange(pullRequest);
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// Git revision for the first commit the pull request is based on.
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const baseRevision = this.getPullRequestBaseRevision(pullRequest);
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// By default, we rebase the pull request so that fixup or squash commits are
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// automatically collapsed. Optionally, if a commit message fixup is needed, we
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// make this an interactive rebase so that commits can be selectively modified
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// before the merge completes.
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const branchBeforeRebase = this.git.getCurrentBranch();
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const rebaseArgs = ['--autosquash', baseRevision, TEMP_PR_HEAD_BRANCH];
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if (needsCommitMessageFixup) {
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this.git.run(['rebase', '--interactive', ...rebaseArgs], {stdio: 'inherit'});
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} else {
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this.git.run(['rebase', ...rebaseArgs]);
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}
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// Update pull requests commits to reference the pull request. This matches what
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// Github does when pull requests are merged through the Web UI. The motivation is
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// that it should be easy to determine which pull request contained a given commit.
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// **Note**: The filter-branch command relies on the working tree, so we want to make
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// sure that we are on the initial branch where the merge script has been run.
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this.git.run(['checkout', '-f', branchBeforeRebase]);
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this.git.run(
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['filter-branch', '-f', '--msg-filter', `${MSG_FILTER_SCRIPT} ${prNumber}`, revisionRange]);
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// Cherry-pick the pull request into all determined target branches.
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const failedBranches = this.cherryPickIntoTargetBranches(revisionRange, targetBranches);
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if (failedBranches.length) {
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return PullRequestFailure.mergeConflicts(failedBranches);
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}
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this.pushTargetBranchesUpstream(targetBranches);
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return null;
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}
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}
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