feat: Add merge-method option

CHANGELOG.md

@@ -1,5 +1,11 @@
 # changelog
 
+HEAD
+
+- Add option to set merge method (merge, squash or rebase). (Example: `mp merge --merge-method squash`)
+
+---
+
 2021-05-22 - v0.0.32
 
 - Adds - `--diff` flag added to `mp plan` to show the diff of the changes made in each repo

cmd/merge.go

@@ -19,6 +19,7 @@ import (
 var mergeFlagThrottle string
 var mergeFlagIgnoreReviewApproval bool
 var mergeFlagIgnoreBuildStatus bool
+var mergeMethod string
 
 // rate limits the # of PR merges. used to prevent load on CI system
 var mergeThrottle *time.Ticker
@@ -92,6 +93,7 @@ func mergeOneRepo(r lib.Repo, ctx context.Context) error {
 		CommitSHA:             pushOutput.CommitSHA,
 		RequireReviewApproval: !mergeFlagIgnoreReviewApproval,
 		RequireBuildSuccess:   !mergeFlagIgnoreBuildStatus,
+		MergeMethod:           mergeMethod,
 	}
 	var output merge.Output
 	if r.IsGitlab() {

cmd/root.go

@@ -34,6 +34,7 @@ func init() {
 	mergeCmd.Flags().StringVarP(&mergeFlagThrottle, "throttle", "t", "30s", "Throttle number of merges, e.g. '30s' means 1 merge per 30 seconds")
 	mergeCmd.Flags().BoolVar(&mergeFlagIgnoreReviewApproval, "ignore-review-approval", false, "Ignore whether or not the review has been approved")
 	mergeCmd.Flags().BoolVar(&mergeFlagIgnoreBuildStatus, "ignore-build-status", false, "Ignore whether or not builds are passing")
+	mergeCmd.Flags().StringVarP(&mergeMethod, "merge-method", "m", "merge", "Merge method to use. Possible values include: merge, squash, and rebase")
 
 	rootCmd.AddCommand(planCmd)
 	planCmd.Flags().StringVarP(&planFlagBranch, "branch", "b", "", "Git branch to commit to")

merge/merge.go

@@ -23,6 +23,8 @@ type Input struct {
 	RequireReviewApproval bool
 	// RequireBuildSuccess specifies if the PR must have a successful build before merging
 	RequireBuildSuccess bool
+	// Merge method to use. Possible values include: "merge", "squash", and "rebase"
+	MergeMethod string
 }
 
 // Output from Push()
@@ -95,7 +97,9 @@ func GitHubMerge(ctx context.Context, input Input, repoLimiter *time.Ticker, mer
 	}
 
 	// Merge the PR
-	options := &github.PullRequestOptions{}
+	options := &github.PullRequestOptions{
+		MergeMethod: input.MergeMethod,
+	}
 	commitMsg := ""
 	<-mergeLimiter.C
 	<-repoLimiter.C