Re: [PATCH v14 6/6] branch: add --dry-run for --prune-merged

[Phillip Wood <phillip.wood123@gmail.com>]

Hi Harald

On 09/06/2026 11:11, Harald Nordgren via GitGitGadget wrote:
> From: Harald Nordgren <haraldnordgren@gmail.com>
> 
> With --dry-run, --prune-merged prints the local branches it would
> delete, one "Would delete branch <name>" line each, and exits
> without touching any ref. The same filtering applies, so the output
> is exactly the set that the real run would delete.

I can see this being very useful.

> diff --git a/builtin/branch.c b/builtin/branch.c
> index 52a0371292..7c52a88af2 100644
> --- a/builtin/branch.c
> +++ b/builtin/branch.c
> @@ -717,7 +717,7 @@ static int parse_opt_forked(const struct option *opt, const char *arg, int unset
>   }
>   
>   static int prune_merged_branches(int argc, const char **argv,
> -				 int quiet)
> +				 int quiet, int dry_run)

Let's not start adding multiple boolean augments - use a flags argument 
like we do for delete_branches() - if you get feedback on one patch you 
should think about whether it applies later in the series as well. The 
rest of the implementation looks good.

> diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
> index 3f7b1fc3d6..305c0141fc 100755
> --- a/t/t3200-branch.sh
> +++ b/t/t3200-branch.sh
> @@ -2040,4 +2040,48 @@ test_expect_success 'branch -d still deletes a pruneMerged=false branch' '
>   	test_must_fail git -C pm-optout-d rev-parse --verify refs/heads/one
>   '
>   
> +test_expect_success '--prune-merged --dry-run lists but does not delete' '

A good way to test --dry-run would be to add it to an existing test 
before calling --prune-merged without --dry-run.

Thanks

Phillip

> +	test_when_finished "rm -rf pm-dry" &&
> +	git clone pm-upstream pm-dry &&
> +	git -C pm-dry remote add fork ../pm-fork &&
> +	test_config -C pm-dry remote.pushDefault fork &&
> +	test_config -C pm-dry push.default current &&
> +	git -C pm-dry branch one one-commit &&
> +	git -C pm-dry branch --set-upstream-to=origin/next one &&
> +	git -C pm-dry branch two two-commit &&
> +	git -C pm-dry branch --set-upstream-to=origin/next two &&
> +
> +	git -C pm-dry branch --dry-run --prune-merged "origin/*" >actual &&
> +	test_grep "Would delete branch one " actual &&
> +	test_grep "Would delete branch two " actual &&
> +
> +	git -C pm-dry rev-parse --verify refs/heads/one &&
> +	git -C pm-dry rev-parse --verify refs/heads/two
> +'
> +
> +test_expect_success '--prune-merged --dry-run only lists branches the live run would delete' '
> +	test_when_finished "rm -rf pm-dry-mixed" &&
> +	git clone pm-upstream pm-dry-mixed &&
> +	git -C pm-dry-mixed remote add fork ../pm-fork &&
> +	test_config -C pm-dry-mixed remote.pushDefault fork &&
> +	test_config -C pm-dry-mixed push.default current &&
> +	git -C pm-dry-mixed checkout -b wip origin/next &&
> +	git -C pm-dry-mixed branch --set-upstream-to=origin/next wip &&
> +	test_commit -C pm-dry-mixed local-only &&
> +	git -C pm-dry-mixed checkout - &&
> +	git -C pm-dry-mixed branch merged one-commit &&
> +	git -C pm-dry-mixed branch --set-upstream-to=origin/next merged &&
> +
> +	git -C pm-dry-mixed branch --dry-run --prune-merged "origin/*" >out &&
> +	test_grep "Would delete branch merged" out &&
> +	test_grep ! "Would delete branch wip" out &&
> +	git -C pm-dry-mixed rev-parse --verify refs/heads/wip &&
> +	git -C pm-dry-mixed rev-parse --verify refs/heads/merged
> +'
> +
> +test_expect_success '--dry-run without --prune-merged is rejected' '
> +	test_must_fail git -C forked branch --dry-run 2>err &&
> +	test_grep "requires --prune-merged" err
> +'
> +
>   test_done