add some tests

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "audiotags"
-version = "0.1.0"
+version = "0.1.3"
 authors = ["Tianyi <ShiTianyi2001@outlook.com>"]
 edition = "2018"
 description = "Unified IO for different types of audio metadata"

tests/io.rs

@@ -0,0 +1,54 @@
+use audiotags::{MimeType, Picture};
+
+macro_rules! test_file {
+    ( $function:ident, $file:expr ) => {
+        #[test]
+        fn $function() {
+            let mut tags = audiotags::read_from_path($file).unwrap();
+            tags.set_title("foo title");
+            assert_eq!(tags.title(), Some("foo title"));
+            tags.remove_title();
+            assert!(tags.title().is_none());
+            tags.remove_title(); // should not panic
+
+            tags.set_artist("foo artist");
+            assert_eq!(tags.artist(), Some("foo artist"));
+            tags.remove_artist();
+            assert!(tags.artist().is_none());
+            tags.remove_artist();
+
+            tags.set_year(2020);
+            assert_eq!(tags.year(), Some(2020));
+            tags.remove_year();
+            assert!(tags.year().is_none());
+            tags.remove_year();
+
+            tags.set_album_title("foo album title");
+            assert_eq!(tags.album_title(), Some("foo album title"));
+            tags.remove_album_title();
+            assert!(tags.album_title().is_none());
+            tags.remove_album_title();
+
+            tags.set_album_artist("foo album artist");
+            assert_eq!(tags.album_artist(), Some("foo album artist"));
+            tags.remove_album_artist();
+            assert!(tags.album_artist().is_none());
+            tags.remove_album_artist();
+
+            let cover = Picture {
+                mime_type: MimeType::Jpeg,
+                data: vec![0u8; 10],
+            };
+
+            tags.set_album_cover(cover.clone());
+            assert_eq!(tags.album_cover(), Some(cover));
+            tags.remove_album_cover();
+            assert!(tags.album_cover().is_none());
+            tags.remove_album_cover();
+        }
+    };
+}
+
+test_file!(test_mp3, "assets/a.mp3");
+test_file!(test_m4a, "assets/a.m4a");
+test_file!(test_flac, "assets/a.flac");