chore(rustup): test installed toolchains (#1684)

### Test
- Emulate `rustup toolchain --quiet` for legacy rustup versions

Author: Emilgardis

src/rustup.rs

@@ -84,15 +84,19 @@ pub fn active_toolchain(msg_info: &mut MessageInfo) -> Result<String> {
 }
 
 pub fn installed_toolchains(msg_info: &mut MessageInfo) -> Result<Vec<String>> {
-    let out = rustup_command(msg_info, true)
-        .args(["toolchain", "list"]) // --quiet would be available from 1.28.0
-        .run_and_get_stdout(msg_info)?;
+    Ok(remove_toolchain_suffixes(
+        rustup_command(msg_info, true)
+            .args(["toolchain", "list"]) // --quiet would be available from 1.28.0
+            .run_and_get_stdout(msg_info)?,
+    ))
+}
 
-    // Emulate --quiet by removing suffixes like " (active, default)" or " (override)" manually
-    Ok(out
+pub(crate) fn remove_toolchain_suffixes<S: AsRef<str>>(out: S) -> Vec<String> {
+    // Emulate --quiet by removing suffixes like " (active, default)" manually
+    out.as_ref()
         .lines()
         .map(|l| l.split_once(" (").map_or(l.trim(), |(a, _)| a).to_owned())
-        .collect())
+        .collect()
 }
 
 pub fn available_targets(

src/tests.rs

@@ -1,3 +1,4 @@
+mod rustup;
 mod toml;
 
 use std::{

src/tests/rustup.rs

@@ -0,0 +1,29 @@
+use crate::rustup;
+
+#[test]
+fn remove_toolchain_suffixes() {
+    // no overrides (default is active)
+    assert_eq!(
+        rustup::remove_toolchain_suffixes(
+            "stable-aarch64-apple-darwin (active, default)\n\
+             stable-x86_64-unknown-linux-gnu"
+        ),
+        vec![
+            "stable-aarch64-apple-darwin",
+            "stable-x86_64-unknown-linux-gnu",
+        ]
+    );
+    // with overrides (default is not active)
+    assert_eq!(
+        rustup::remove_toolchain_suffixes(
+            "stable-aarch64-apple-darwin (default)\n\
+             stable-x86_64-unknown-linux-gnu\n\
+             nightly-aarch64-apple-darwin (active)"
+        ),
+        vec![
+            "stable-aarch64-apple-darwin",
+            "stable-x86_64-unknown-linux-gnu",
+            "nightly-aarch64-apple-darwin",
+        ]
+    );
+}