test(shell): cover kind fallback and shell arguments

crates/moon-util/src/shell.rs

@@ -693,6 +693,9 @@ impl ShellKind {
     }
 }
 
+#[cfg(test)]
+mod shell_tests;
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/moon-util/src/shell/shell_tests.rs

@@ -0,0 +1,82 @@
+use super::ShellKind;
+
+/// Catches `ShellKind::new` sending an unknown program to POSIX on Windows,
+/// so a task would look for `sh` and fail to start a shell.
+#[test]
+fn unknown_program_falls_back_to_powershell_only_on_windows() {
+    assert_eq!(ShellKind::new("cmd.exe", false), ShellKind::Cmd);
+    assert_eq!(
+        ShellKind::new("powershell.exe", true),
+        ShellKind::PowerShell
+    );
+    assert_eq!(ShellKind::new("pwsh", false), ShellKind::Pwsh);
+    assert_eq!(ShellKind::new("bash", false), ShellKind::Posix);
+    assert_eq!(ShellKind::new("fancy", true), ShellKind::PowerShell);
+    assert_eq!(ShellKind::new("fancy", false), ShellKind::Posix);
+}
+
+/// Catches `to_cmd_variable` rewriting `${VAR:-default}` into a percent name,
+/// so cmd would look up `VAR:-default` instead of keeping the default text.
+#[test]
+fn cmd_rewrites_variables_but_leaves_default_substitutions() {
+    assert_eq!(ShellKind::Cmd.to_shell_variable("$FOO"), "%FOO%");
+    assert_eq!(ShellKind::Cmd.to_shell_variable("${FOO}"), "%FOO%");
+    assert_eq!(
+        ShellKind::Cmd.to_shell_variable("${FOO:-bar}"),
+        "${FOO:-bar}"
+    );
+    assert_eq!(ShellKind::Cmd.to_shell_variable("plain"), "plain");
+}
+
+/// Catches `to_powershell_variable` leaving `$FOO` as a local variable, so a
+/// PowerShell task would miss the environment value the caller set.
+#[test]
+fn powershell_rewrites_variables_onto_the_env_drive() {
+    assert_eq!(ShellKind::PowerShell.to_shell_variable("$FOO"), "$env:FOO");
+    assert_eq!(ShellKind::Pwsh.to_shell_variable("${BAR}"), "$env:BAR");
+    assert_eq!(
+        ShellKind::PowerShell.to_shell_variable("${FOO:-bar}"),
+        "${FOO:-bar}"
+    );
+    assert_eq!(ShellKind::Pwsh.to_shell_variable("plain"), "plain");
+}
+
+/// Catches `args_for_shell` dropping the quotes around a cmd `/C` payload, so
+/// cmd would split `echo hi` on the space and run a different command.
+#[test]
+fn cmd_args_quote_the_command_and_ignore_interactive() {
+    let command = "echo hi".to_owned();
+    let expected = vec!["/S".to_owned(), "/C".to_owned(), "\"echo hi\"".to_owned()];
+    assert_eq!(
+        ShellKind::Cmd.args_for_shell(true, command.clone()),
+        expected
+    );
+    assert_eq!(ShellKind::Cmd.args_for_shell(false, command), expected);
+}
+
+/// Catches `args_for_shell` passing `-c` or `-i` to Windows PowerShell, so
+/// the process would reject the flag and the task would not run.
+#[test]
+fn powershell_args_use_capital_c_without_an_interactive_flag() {
+    let command = "echo hi".to_owned();
+    let expected = vec!["-C".to_owned(), "echo hi".to_owned()];
+    assert_eq!(
+        ShellKind::PowerShell.args_for_shell(true, command.clone()),
+        expected
+    );
+    assert_eq!(ShellKind::Pwsh.args_for_shell(false, command), expected);
+}
+
+/// Catches `args_for_shell` always passing `-i` to a POSIX shell, so a
+/// non-interactive task would start an interactive shell and wait on stdin.
+#[test]
+fn posix_args_add_interactive_only_when_requested() {
+    assert_eq!(
+        ShellKind::Posix.args_for_shell(false, "echo hi".to_owned()),
+        vec!["-c".to_owned(), "echo hi".to_owned()]
+    );
+    assert_eq!(
+        ShellKind::Fish.args_for_shell(true, "echo hi".to_owned()),
+        vec!["-i".to_owned(), "-c".to_owned(), "echo hi".to_owned()]
+    );
+}