Get tests working in parallel

Instead of a single temporary directory, we just create one per file and
encapsulate it in a structure, so we can get both the file path and a
temp dir that's dropped upon the struct leaving scope.

tests/test_processing.rs

@@ -1,112 +1,126 @@
 use std::env;
 use std::fs;
-use std::path::PathBuf;
+use std::path::{PathBuf, Path};
+use std::ops::Deref;
 
+use tempfile::TempDir;
 use id3_image::*;
 
-macro_rules! in_temp_dir {
+struct Fixture {
-    ($block:block) => {
+    path_buf: PathBuf,
-        let tmpdir = tempfile::tempdir().unwrap();
+    _tempdir: TempDir,
-        env::set_current_dir(&tmpdir).unwrap();
+}
 
-        $block;
+impl AsRef<Path> for Fixture {
+    fn as_ref(&self) -> &Path {
+        self.path_buf.as_path()
+    }
+}
+
+impl Deref for Fixture {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        self.path_buf.to_str().unwrap()
     }
 }
 
 macro_rules! fixture {
     ($filename:expr) => {
+        {
             let root_dir = &env::var("CARGO_MANIFEST_DIR").expect("$CARGO_MANIFEST_DIR");
             let mut source_path = PathBuf::from(root_dir);
             source_path.push("tests/fixtures");
             source_path.push($filename);
 
-        fs::copy(source_path, $filename).unwrap();
+            let tempdir = tempfile::tempdir().unwrap();
+            let mut target_path = PathBuf::from(&tempdir.path());
+            target_path.push($filename);
+
+            fs::copy(&source_path, &target_path).unwrap();
+
+            Fixture { _tempdir: tempdir, path_buf: target_path }
         }
     }
+}
+
+fn read_tag(path: &str) -> id3::Tag {
+    id3::Tag::read_from_path(path).unwrap()
+}
 
 #[test]
 fn test_unsuccessful_image_embedding() {
-    in_temp_dir!({
+    let song  = fixture!("attempt_1_no_image.mp3");
-        fixture!("attempt_1_no_image.mp3");
+    let image = fixture!("attempt_1.jpg");
-        fixture!("attempt_1.jpg");
 
     // Nonexistent files
-        assert!(embed_image("attempt_1_no_image.mp3", "nonexisting.jpg").is_err());
+    assert!(embed_image(&song, "nonexisting.jpg").is_err());
-        assert!(embed_image("nonexisting.mp3", "attempt_1.jpg").is_err());
+    assert!(embed_image("nonexisting.mp3", &image).is_err());
     assert!(embed_image("nonexisting.mp3", "nonexisting.jpg").is_err());
 
     // Wrong kinds of files
-        assert!(embed_image("attempt_1.jpg", "attempt_1_no_image.mp3").is_err());
+    assert!(embed_image(&image, &song).is_err());
-        assert!(embed_image("attempt_1_no_image.mp3", "attempt_1_no_image.mp3").is_err());
+    assert!(embed_image(&song, &song).is_err());
-        assert!(embed_image("attempt_1.jpg", "attempt_1.jpg").is_err());
+    assert!(embed_image(&image, &image).is_err());
-    });
 }
 
 #[test]
 fn test_successful_jpeg_image_embedding() {
-    in_temp_dir!({
+    let song  = fixture!("attempt_1_no_image.mp3");
-        fixture!("attempt_1_no_image.mp3");
+    let image = fixture!("attempt_1.jpg");
-        fixture!("attempt_1.jpg");
 
-        let tag = id3::Tag::read_from_path("attempt_1_no_image.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() == 0);
 
-        embed_image("attempt_1_no_image.mp3", "attempt_1.jpg").unwrap();
+    embed_image(&song, &image).unwrap();
 
-        let tag = id3::Tag::read_from_path("attempt_1_no_image.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() > 0);
-    });
 }
 
 #[test]
 fn test_successful_png_image_embedding() {
-    in_temp_dir!({
+    let song  = fixture!("attempt_1_no_image.mp3");
-        fixture!("attempt_1_no_image.mp3");
+    let image = fixture!("attempt_1.png");
-        fixture!("attempt_1.png");
 
-        let tag = id3::Tag::read_from_path("attempt_1_no_image.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() == 0);
 
-        embed_image("attempt_1_no_image.mp3", "attempt_1.png").unwrap();
+    embed_image(&song, &image).unwrap();
 
-        let tag = id3::Tag::read_from_path("attempt_1_no_image.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() > 0);
-    });
 }
 
 #[test]
 fn test_successful_image_embedding_in_a_file_that_already_has_an_image() {
-    in_temp_dir!({
+    let song  = fixture!("attempt_1.mp3");
-        fixture!("attempt_1.mp3");
+    let image = fixture!("attempt_1.jpg");
-        fixture!("attempt_1.jpg");
 
-        let tag = id3::Tag::read_from_path("attempt_1.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() > 0);
 
-        embed_image("attempt_1.mp3", "attempt_1.jpg").unwrap();
+    embed_image(&song, &image).unwrap();
 
-        let tag = id3::Tag::read_from_path("attempt_1.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() > 0);
-    });
 }
 
 #[test]
 fn test_remove_and_add_image() {
-    in_temp_dir!({
+    let song  = fixture!("attempt_1.mp3");
-        fixture!("attempt_1.mp3");
+    let image = fixture!("attempt_1.jpg");
-        fixture!("attempt_1.jpg");
 
-        let tag = id3::Tag::read_from_path("attempt_1.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() > 0);
 
-        remove_images("attempt_1.mp3").unwrap();
+    remove_images(&song).unwrap();
 
-        let tag = id3::Tag::read_from_path("attempt_1.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() == 0);
 
-        embed_image("attempt_1.mp3", "attempt_1.jpg").unwrap();
+    embed_image(&song, &image).unwrap();
 
-        let tag = id3::Tag::read_from_path("attempt_1.mp3").unwrap();
+    let tag = read_tag(&song);
     assert!(tag.pictures().count() > 0);
-    });
 }