start schema work

src/lib.rs

@@ -0,0 +1,65 @@
+#[derive(PartialEq, Eq, Debug)]
+pub enum SchemaState {
+    Unknown,
+    Null,
+    String,
+    Number,
+    Boolean,
+    Array(Box<SchemaState>),
+    Object {
+        required: Vec<(String, SchemaState)>,
+        optional: Vec<(String, SchemaState)>,
+    },
+}
+
+pub fn merge_state(current_state: SchemaState, new_state: SchemaState) -> SchemaState {
+    SchemaState::Unknown
+}
+
+#[cfg(test)]
+mod test {
+    mod merge {
+        use crate::{merge_state, SchemaState};
+
+        #[test]
+        fn anything_merged_with_unknown_yields_unknown() {
+            assert_eq!(
+                merge_state(SchemaState::Unknown, SchemaState::Unknown),
+                SchemaState::Unknown
+            );
+            assert_eq!(
+                merge_state(SchemaState::Null, SchemaState::Unknown),
+                SchemaState::Unknown
+            );
+            assert_eq!(
+                merge_state(SchemaState::String, SchemaState::Unknown),
+                SchemaState::Unknown
+            );
+            assert_eq!(
+                merge_state(SchemaState::Number, SchemaState::Unknown),
+                SchemaState::Unknown
+            );
+            assert_eq!(
+                merge_state(SchemaState::Boolean, SchemaState::Unknown),
+                SchemaState::Unknown
+            );
+            assert_eq!(
+                merge_state(
+                    SchemaState::Array(Box::new(SchemaState::Number)),
+                    SchemaState::Unknown
+                ),
+                SchemaState::Unknown
+            );
+            assert_eq!(
+                merge_state(
+                    SchemaState::Object {
+                        required: vec![("foo".to_owned(), SchemaState::Boolean)],
+                        optional: Vec::new()
+                    },
+                    SchemaState::Unknown
+                ),
+                SchemaState::Unknown
+            );
+        }
+    }
+}