radicle-cli/tests: `fn program_reports_version`

Introduce this `fn` to check whether a program is available.

crates/radicle-cli/tests/commands.rs

@@ -1,3 +1,4 @@
+use core::panic;
 use std::path::Path;
 use std::str::FromStr;
 use std::{fs, net, thread, time};
@@ -50,6 +51,32 @@ pub(crate) fn test<'a>(
     Ok(())
 }
 
+/// A utility to check that some program can be executed with a `--version`
+/// argument and exits successfully.
+///
+/// # Panics
+///
+/// If there is an error executing the program other than the program not being
+/// found, or the program does not exit successfully.
+fn program_reports_version(program: &str) -> bool {
+    use std::io::ErrorKind;
+    use std::process::{Command, Stdio};
+
+    match Command::new(program)
+        .arg("--version")
+        .stdout(Stdio::null())
+        .status()
+    {
+        Err(e) if e.kind() == ErrorKind::NotFound => {
+            log::warn!(target: "test", "`{program}` not found.");
+            false
+        }
+        Err(e) => panic!("failure to execute `{program}`: {e}"),
+        Ok(status) if status.success() => true,
+        Ok(status) => panic!("executing `{program}` resulted in status {status}"),
+    }
+}
+
 #[test]
 fn rad_auth() {
     test("examples/rad-auth.md", Path::new("."), None, []).unwrap();
@@ -111,21 +138,11 @@ fn rad_cob_update_identity() {
 
 #[test]
 fn rad_cob_multiset() {
-    {
-        // `rad-cob-multiset` is a `jq` script, which requires `jq` to be installed.
-        // We test whether `jq` is installed, and have this test succeed if it is not.
-        // Programmatic skipping of tests is not supported as of 2024-08.
-        use std::io::ErrorKind;
-        use std::process::{Command, Stdio};
-
-        match Command::new("jq").arg("-V").stdout(Stdio::null()).status() {
-            Err(e) if e.kind() == ErrorKind::NotFound => {
-                log::warn!(target: "test", "`jq` not found. Succeeding prematurely.");
-                return;
-            }
-            Err(e) => panic!("while checking for jq: {e}"),
-            Ok(_) => {}
-        }
+    // `rad-cob-multiset` is a `jq` script, which requires `jq` to be installed.
+    // We test whether `jq` is installed, and have this test succeed if it is not.
+    // Programmatic skipping of tests is not supported as of 2024-08.
+    if !program_reports_version("jq") {
+        return;
     }
 
     let mut environment = Environment::new();