test: add smoke tests for shell completions

Author: MilesCranmer

tests/command_completions_test.rs

@@ -0,0 +1,55 @@
+use assert_cmd::Command;
+use predicates::prelude::*;
+
+fn test_shell_completion(shell: &str, expected_patterns: &[&str]) {
+    let depot_dir = tempfile::Builder::new()
+        .prefix("juliauptest")
+        .tempdir()
+        .unwrap();
+
+    let mut cmd = Command::cargo_bin("juliaup")
+        .unwrap()
+        .arg("completions")
+        .arg(shell)
+        .env("JULIA_DEPOT_PATH", depot_dir.path())
+        .env("JULIAUP_DEPOT_PATH", depot_dir.path())
+        .assert()
+        .success();
+
+    for pattern in expected_patterns {
+        cmd = cmd.stdout(predicate::str::contains(*pattern));
+    }
+}
+
+#[test]
+fn completions_bash() {
+    test_shell_completion("bash", &["_juliaup()", "complete -F _juliaup"]);
+}
+
+#[test]
+fn completions_zsh() {
+    test_shell_completion("zsh", &["#compdef juliaup", "_juliaup()"]);
+}
+
+#[test]
+fn completions_fish() {
+    test_shell_completion("fish", &["complete -c juliaup", "-n \"__fish"]);
+}
+
+#[test]
+fn completions_powershell() {
+    test_shell_completion("power-shell", &["Register-ArgumentCompleter", "juliaup"]);
+}
+
+#[test]
+fn completions_elvish() {
+    test_shell_completion("elvish", &["edit:completion:arg-completer", "juliaup"]);
+}
+
+#[test]
+fn completions_nushell() {
+    test_shell_completion(
+        "nushell",
+        &["module completions", "export extern juliaup", "export use completions"],
+    );
+}