test: cover exact package tool invocation paths

test/testenv/testenv.ww

@@ -76,6 +76,17 @@ export fn writefile(path: str, content: str) void = {
 	assert(os.close(fd) == 0);
 };
 
+export fn writeexecutable(path: str, content: str) void = {
+	let fd: i32 = os.open(path,
+		os.flag.WRONLY | os.flag.CREATE | os.flag.EXCL, 448i32);
+	assert(fd >= 0);
+	match (os.writeall(fd, content.ptr, content.len: u64)) {
+	case let n: i64 => assert(n == content.len: i64);
+	case let e: os.oserror => abort("write failed");
+	};
+	assert(os.close(fd) == 0);
+};
+
 export fn exists(path: str) bool = {
 	return os.access(path, 0i32) == 0;
 };