test(app): reject root errors before initialization

apps/vectorcraft/tests/automation_args.rs

@@ -0,0 +1,70 @@
+// Integration tests may panic on failure (AGENTS.md › Robustness).
+#![allow(clippy::unwrap_used, clippy::expect_used, clippy::panic)]
+
+use std::process::{Command, Stdio};
+use std::time::{Duration, Instant};
+
+const BIN: &str = env!("CARGO_BIN_EXE_vectorcraft");
+
+/// Invalid roots must exit before desktop initialization on every platform, including a CI
+/// machine with no display. A regression must fail rather than hang with a window open.
+fn rejects(args: &[&str], message: &str) {
+    let mut child = Command::new(BIN)
+        .args(args)
+        .env_remove("VECTORCRAFT_CONTROL_PORT")
+        .env_remove("VECTORCRAFT_AUTOMATION_READ_ROOT")
+        .env_remove("VECTORCRAFT_AUTOMATION_WRITE_ROOT")
+        .env("VECTORCRAFT_NO_PREFS", "1")
+        .stdin(Stdio::null())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    let deadline = Instant::now() + Duration::from_secs(5);
+    let timed_out = loop {
+        if child.try_wait().unwrap().is_some() {
+            break false;
+        }
+        if Instant::now() >= deadline {
+            child.kill().unwrap();
+            break true;
+        }
+        std::thread::sleep(Duration::from_millis(10));
+    };
+    let out = child.wait_with_output().unwrap();
+    assert!(!timed_out, "{args:?}: desktop started or did not exit promptly");
+    assert!(!out.status.success(), "{args:?}");
+    assert!(out.stdout.is_empty(), "{args:?}: {:?}", out.stdout);
+    // Exact stderr excludes unrelated startup warnings or display errors that could otherwise
+    // make a malformed invocation fail for an unrelated reason.
+    assert_eq!(String::from_utf8(out.stderr).unwrap(), format!("vectorcraft: {message}\n"), "{args:?}");
+}
+
+#[test]
+fn missing_empty_or_option_operands_fail_before_startup() {
+    for flag in ["--automation-read-root", "--automation-write-root"] {
+        rejects(&["--control", "7979", flag], &format!("{flag} needs a folder"));
+        rejects(&[flag], &format!("{flag} needs a folder"));
+        rejects(&["--control", "7979", &format!("{flag}=")], &format!("{flag} needs a non-empty folder"));
+        rejects(&[flag, ""], &format!("{flag} needs a non-empty folder"));
+        for next in ["--version", "--control", "--automation-write-root", "-folder"] {
+            rejects(&[flag, next], &format!("{flag} needs a folder; use {flag}=<dir> for a folder starting with '-'"));
+        }
+    }
+}
+
+#[test]
+fn duplicate_roots_fail_for_both_spellings() {
+    for flag in ["--automation-read-root", "--automation-write-root"] {
+        rejects(&[flag, ".", &format!("{flag}=.")], &format!("{flag} given twice"));
+        rejects(&[&format!("{flag}=."), flag, "."], &format!("{flag} given twice"));
+    }
+}
+
+#[test]
+fn explicit_dash_folder_does_not_consume_version() {
+    let out = Command::new(BIN).args(["--automation-read-root=-folder", "--automation-write-root", "./-folder", "--version"]).output().unwrap();
+    assert!(out.status.success(), "{}", String::from_utf8_lossy(&out.stderr));
+    assert_eq!(String::from_utf8(out.stdout).unwrap(), format!("vectorcraft {}\n", env!("CARGO_PKG_VERSION")));
+    assert!(out.stderr.is_empty());
+}