Add tests

tests/struct_adapter_test.v

@@ -0,0 +1,35 @@
+import structlog
+
+struct Simple {
+	foo int
+	bar string
+}
+
+fn test_struct_adapter() {
+	assert structlog.struct_adapter(Simple{10, 'fooo'}) == [
+		structlog.Field{'foo', 10},
+		structlog.Field{'bar', 'fooo'},
+	]
+}
+
+/* FIXME
+enum SomeEnum {
+	one
+	two
+	three
+}
+
+struct WithEnum {
+	foo       int
+	bar       string
+	some_enum SomeEnum
+}
+
+fn test_struct_adapter_with_enum() {
+	assert structlog.struct_adapter(WithEnum{10, 'fooo', .two}) == [
+		structlog.Field{'foo', 10},
+		structlog.Field{'bar', 'fooo'},
+		structlog.Field{'some_enum', 'two'},
+	]
+}
+*/