test: add helpers for checking (negative) errnos

This way we get to see the actual error when it happens.

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/984>

test/litest.c

@@ -792,10 +792,10 @@ litest_init_all_device_udev_rules(struct list *created_files)
 	rc = xasprintf(&path,
 		      "%s/99-litest-XXXXXX.rules",
 		      UDEV_RULES_D);
-	litest_assert_int_gt(rc, 0);
+	litest_assert_errno_success(rc);
 
 	fd = mkstemps(path, 6);
-	litest_assert_int_ne(fd, -1);
+	litest_assert_errno_success(fd);
 	f = fdopen(fd, "w");
 	litest_assert_notnull(f);
 
@@ -1687,7 +1687,7 @@ litest_create(enum litest_device_type which,
 	litest_assert_int_ne(fd, -1);
 
 	rc = libevdev_new_from_fd(fd, &d->evdev);
-	litest_assert_int_eq(rc, 0);
+	litest_assert_neg_errno_success(rc);
 
 	return d;
 
@@ -1963,7 +1963,7 @@ litest_event(struct litest_device *d, unsigned int type,
 		return;
 
 	ret = libevdev_uinput_write_event(d->uinput, type, code, value);
-	litest_assert_int_eq(ret, 0);
+	litest_assert_neg_errno_success(ret);
 }
 
 static bool
@@ -3049,6 +3049,7 @@ litest_wait_for_event_of_type(struct libinput *li, ...)
 
 		while ((type = libinput_next_event_type(li)) == LIBINPUT_EVENT_NONE) {
 			int rc = poll(&fds, 1, 2000);
+			litest_assert_errno_success(rc);
 			litest_assert_int_gt(rc, 0);
 			libinput_dispatch(li);
 		}

test/litest.h

@@ -161,6 +161,21 @@ litest_fail_comparison_ptr(const char *file,
 						   #a_, #b_); \
 	} while(0)
 
+#define litest_assert_neg_errno_success(a_) \
+	do { \
+		__typeof__(a_) _a = a_; \
+		if (_a < 0) \
+			litest_abort_msg("Unexpected negative errno: %d (%s)", _a, strerror(-_a)); \
+	} while(0);
+
+#define litest_assert_errno_success(a_) \
+	do { \
+		__typeof__(a_) _a = a_; \
+		__typeof__(a_) _e = errno; \
+		if (_a < 0) \
+			litest_abort_msg("Unexpected errno: %d (%s)", _e, strerror(_e)); \
+	} while(0);
+
 #define litest_assert_int_eq(a_, b_) \
 	litest_assert_comparison_int_(a_, ==, b_)
 

test/test-misc.c

@@ -85,7 +85,7 @@ create_simple_test_device(const char *name, ...)
 	rc = libevdev_uinput_create_from_device(evdev,
 						LIBEVDEV_UINPUT_OPEN_MANAGED,
 						&uinput);
-	litest_assert_int_eq(rc, 0);
+	litest_assert_neg_errno_success(rc);
 	libevdev_free(evdev);
 
 	return uinput;

test/test-quirks.c

@@ -65,8 +65,8 @@ make_data_dir(const char *file_content)
 		fp = fopen(filename, "w+");
 		litest_assert_notnull(fp);
 		rc = fputs(file_content, fp);
+		litest_assert_errno_success(rc);
 		fclose(fp);
-		litest_assert_int_ge(rc, 0);
 		dir.filename = filename;
 	}