Match recreated stacks without unrelated merged history

Author: skarim

cmd/checkout.go

@@ -538,24 +538,10 @@ func findLocalStackForRemotePRs(sf *stack.StackFile, prs []*github.PullRequest)
 	return nil
 }
 
-// stackCompositionMatches checks if a local stack's PR numbers match
-// the remote stack's PR numbers in the same order.
+// stackCompositionMatches ignores merged history that belongs to a previous stack.
 func stackCompositionMatches(localStack *stack.Stack, remotePRNumbers []int) bool {
-	var localPRNumbers []int
-	for _, b := range localStack.Branches {
-		if b.PullRequest != nil {
-			localPRNumbers = append(localPRNumbers, b.PullRequest.Number)
-		}
-	}
-	if len(localPRNumbers) != len(remotePRNumbers) {
-		return false
-	}
-	for i := range localPRNumbers {
-		if localPRNumbers[i] != remotePRNumbers[i] {
-			return false
-		}
-	}
-	return true
+	localPRNumbers := stackPRNumbers(localStack, &github.RemoteStack{PullRequests: remotePRNumbers})
+	return slicesEqual(localPRNumbers, remotePRNumbers)
 }
 
 // handleCompositionConflict prompts the user to resolve a mismatch between

cmd/checkout_test.go

@@ -1341,6 +1341,28 @@ func TestStackCompositionMatches(t *testing.T) {
 			remote:  []int{10, 11},
 			matches: true,
 		},
+		{
+			name: "merged history from a previous stack",
+			local: &stack.Stack{
+				Branches: []stack.BranchRef{
+					{Branch: "a", PullRequest: &stack.PullRequestRef{Number: 10, Merged: true}},
+					{Branch: "b", PullRequest: &stack.PullRequestRef{Number: 11}},
+				},
+			},
+			remote:  []int{11},
+			matches: true,
+		},
+		{
+			name: "merged member of the current stack",
+			local: &stack.Stack{
+				Branches: []stack.BranchRef{
+					{Branch: "a", PullRequest: &stack.PullRequestRef{Number: 10, Merged: true}},
+					{Branch: "b", PullRequest: &stack.PullRequestRef{Number: 11}},
+				},
+			},
+			remote:  []int{10, 11},
+			matches: true,
+		},
 		{
 			name: "different order",
 			local: &stack.Stack{