add basic snapshot testing

tests/tests.rs

@@ -0,0 +1,30 @@
+use std::fs;
+use pretty_assertions::assert_eq;
+
+use tf_demo_parser::{Demo, DemoParser, Stream, MatchState};
+
+fn snapshot_test(input_file: &str, snapshot_file: &str) {
+    let file = fs::read(input_file).expect("Unable to read file");
+    let demo = Demo::new(file);
+    let stream: Stream = demo.get_stream();
+    let parser = DemoParser::new(stream);
+    let (_, state) = parser.parse_demo().unwrap();
+
+    let expected: MatchState = serde_json::from_slice(fs::read(snapshot_file).expect("Unable to read file").as_slice()).unwrap();
+    assert_eq!(expected, state);
+}
+
+#[test]
+fn snapshot_test_small() {
+    snapshot_test("data/small.dem", "data/small.json");
+}
+
+#[test]
+fn snapshot_test_gully() {
+    snapshot_test("data/gully.dem", "data/gully.json");
+}
+
+#[test]
+fn snapshot_test_comp() {
+    snapshot_test("data/comp.dem", "data/comp.json");
+}