lib/dirs: rows skip loudly when WW_TEST_TMPDIR is absent

lib/dirs/dirs_test.ww

@@ -1,10 +1,13 @@
-// dirstest — exercises lib/dirs against an env state pre-arranged by
-// the C driver (test/wcc/975_dirs_run.c).
+// dirstest — exercises lib/dirs against an arranged env cohort. The
+// XDG rows need env control ww cannot self-arrange (no setenv,
+// deliberately), so every row skips loudly when WW_TEST_TMPDIR is
+// absent and the suite passes bare; the arranged leg (env cohort
+// below constructed per row over a scratch HOME, rows asserted `ok`,
+// not SKIP) is test/libenv/libenv_test.ww.
 //
-// Pre-arranged env (set via setenv/unsetenv before exec'ing
-// `ww run lib/dirs/dirstest.ww`; see 975_dirs_run.c):
+// Arranged env cohort:
 //
-//   HOME             = <tmpl>            (mkdtemp'd /tmp/wwdirs-XXXXXX)
+//   HOME             = <tmpl>            (fresh scratch dir)
 //   XDG_CONFIG_HOME  = <tmpl>/cfg        (absolute → XDG branch)
 //   XDG_CACHE_HOME   = "relative/path"   (non-abs → fallback to HOME)
 //   XDG_DATA_HOME    unset               (fallback to HOME)
@@ -36,6 +39,7 @@ package dirs_test;
 
 import dirs;
 import os;
+import test;
 
 
 
@@ -83,11 +87,8 @@ fn expected(tmpl: str, sub: str, prog: str) str = {
 fn gettmpdir() str = {
 	match (os.getenv("WW_TEST_TMPDIR")) {
 	case let s: str => return s;
-	case void => {
-		abort();
-		let empty: str;
-		return empty;
-	};
+	case void =>
+		test.skip("WW_TEST_TMPDIR unset (arranged leg: test/libenv)");
 	};
 };