test: strengthen durable behavior coverage after review

crates/irtt-app/tests/cli.rs

@@ -1,22 +1,49 @@
-#![cfg(all(feature = "client", feature = "server", feature = "tui"))]
-
+#[cfg(feature = "client")]
 #[path = "../../irtt-integration-tests/tests/support/in_tree_server.rs"]
 mod in_tree_server;
 
+#[cfg(feature = "client")]
 use irtt_server::ServerConfig;
 use std::process::Command;
 
-// The actual binaries own dispatch, argument handling, exit policy and output.
-// A real authenticated server also detects broken argument-to-config mapping.
+// Dispatch/help/availability belong to the application and run in every build.
 #[test]
-fn applets_dispatch_validate_arguments_and_export_a_real_client_run() {
+fn dispatcher_reports_and_runs_the_enabled_applets() {
     let dispatcher = env!("CARGO_BIN_EXE_irtt-rs");
-    for binary in [
-        dispatcher,
-        env!("CARGO_BIN_EXE_irtt-client"),
-        env!("CARGO_BIN_EXE_irtt-server"),
-        env!("CARGO_BIN_EXE_irtt-tui"),
+    let help = Command::new(dispatcher).arg("--help").output().unwrap();
+    assert!(help.status.success());
+    let help = String::from_utf8(help.stdout).unwrap();
+    for (applet, enabled) in [
+        ("client", cfg!(feature = "client")),
+        ("server", cfg!(feature = "server")),
+        ("tui", cfg!(feature = "tui")),
     ] {
+        let row = help
+            .lines()
+            .find(|line| line.trim_start().starts_with(applet))
+            .unwrap();
+        assert_eq!(row.contains("not available"), !enabled);
+        let output = Command::new(dispatcher)
+            .args([applet, "--help"])
+            .output()
+            .unwrap();
+        assert_eq!(output.status.success(), enabled, "{applet}");
+        if !enabled {
+            assert!(String::from_utf8(output.stderr)
+                .unwrap()
+                .contains("not available"));
+        }
+    }
+    let binaries = [
+        dispatcher,
+        #[cfg(feature = "client")]
+        env!("CARGO_BIN_EXE_irtt-client"),
+        #[cfg(feature = "server")]
+        env!("CARGO_BIN_EXE_irtt-server"),
+        #[cfg(feature = "tui")]
+        env!("CARGO_BIN_EXE_irtt-tui"),
+    ];
+    for binary in binaries {
         assert!(Command::new(binary)
             .arg("--help")
             .output()
@@ -30,6 +57,13 @@ fn applets_dispatch_validate_arguments_and_export_a_real_client_run() {
             .status
             .success());
     }
+}
+
+// A real authenticated server detects broken client argument-to-config mapping.
+#[cfg(feature = "client")]
+#[test]
+fn client_arguments_export_a_real_client_run() {
+    let dispatcher = env!("CARGO_BIN_EXE_irtt-rs");
     for option in ["--dscp", "--ttl"] {
         assert!(!Command::new(dispatcher)
             .args(["client", option, "256", "127.0.0.1:9"])