test: valid string slices for ghostty_string_s

src/main_c.zig

@@ -155,3 +155,43 @@ pub export fn ghostty_translate(msgid: [*:0]const u8) [*:0]const u8 {
 pub export fn ghostty_string_free(str: String) void {
     str.deinit();
 }
+
+test "ghostty_string_s empty string" {
+    const testing = std.testing;
+    const empty_string = String.empty;
+    defer empty_string.deinit();
+
+    try testing.expect(empty_string.len == 0);
+    try testing.expect(empty_string.sentinel == false);
+}
+
+test "ghostty_string_s c string" {
+    const testing = std.testing;
+    state.alloc = testing.allocator;
+
+    const slice: [:0]const u8 = "hello";
+    const allocated_slice = try testing.allocator.dupeZ(u8, slice);
+    const c_null_string = String.fromSlice(allocated_slice);
+    defer c_null_string.deinit();
+
+    try testing.expect(allocated_slice[5] == 0);
+    try testing.expect(@TypeOf(slice) == [:0]const u8);
+    try testing.expect(@TypeOf(allocated_slice) == [:0]u8);
+    try testing.expect(c_null_string.len == 5);
+    try testing.expect(c_null_string.sentinel == true);
+}
+
+test "ghostty_string_s zig string" {
+    const testing = std.testing;
+    state.alloc = testing.allocator;
+
+    const slice: []const u8 = "hello";
+    const allocated_slice = try testing.allocator.dupe(u8, slice);
+    const zig_string = String.fromSlice(allocated_slice);
+    defer zig_string.deinit();
+
+    try testing.expect(@TypeOf(slice) == []const u8);
+    try testing.expect(@TypeOf(allocated_slice) == []u8);
+    try testing.expect(zig_string.len == 5);
+    try testing.expect(zig_string.sentinel == false);
+}