feat(cli/test): `deno test --clean` (#23519)

The result of the call is ignored as it throws even when the directory
does not exist.

Closes #23491

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/specs/test/clean_flag/main.js b/tests/specs/test/clean_flag/main.js
new file mode 100644
index 000000000..215c2229c
--- /dev/null
+++ b/tests/specs/test/clean_flag/main.js
@@ -0,0 +1,23 @@
+import { emptyDir } from "../../../util/std/fs/empty_dir.ts";
+
+const DIR = "./coverage";
+const COMMAND = new Deno.Command(Deno.execPath(), {
+  args: ["test", "--coverage", "--clean"],
+  stdout: "null",
+});
+
+async function getCoverageFiles() {
+  return await Array.fromAsync(Deno.readDir(DIR), ({ name }) => name);
+}
+
+await emptyDir(DIR);
+await COMMAND.output();
+const files1 = new Set(await getCoverageFiles());
+
+await COMMAND.output();
+const files2 = new Set(await getCoverageFiles());
+
+console.log(files1.size === files2.size);
+console.log(files1.intersection(files2).size === 0);
+await emptyDir(DIR);
+await Deno.remove(DIR);