Assert file equality

tests/integration.rs

@@ -1,4 +1,8 @@
-use std::path::{Path, PathBuf};
+use std::{
+    fs::{self, File},
+    io::{self, Read},
+    path::{Path, PathBuf},
+};
 
 use tempfile::tempdir;
 
@@ -22,22 +26,22 @@ fn from_empty_dst() {
         phorg::hash::Hash::Crc32,
     )
     .unwrap();
+
+    let foo_before = "foo.jpg";
+    let foo_after = "img/2000/12/27/2000-12-27--06:47:01--crc32:383ba95e.jpg";
+    let bar_before = "bar.jpg";
+    let bar_after = "img/2010/01/31/2010-01-31--17:35:49--crc32:c653b4f3.jpg";
+
     assert_eq!(
         &file_paths_sorted(&src),
-        &vec![src.join("bar.jpg"), src.join("foo.jpg"), src.join("make"),]
+        &vec![src.join(bar_before), src.join(foo_before), src.join("make"),]
     );
     assert_eq!(
         &file_paths_sorted(dst),
-        &vec![
-            dst.join(
-                "img/2000/12/27/2000-12-27--06:47:01--crc32:383ba95e.jpg"
-            ),
-            dst.join(
-                "img/2010/01/31/2010-01-31--17:35:49--crc32:c653b4f3.jpg"
-            ),
-        ]
+        &vec![dst.join(foo_after), dst.join(bar_after),]
     );
-    // TODO Assert file contents did not change.
+    assert!(files_eq(src.join(foo_before), dst.join(foo_after)).unwrap());
+    assert!(files_eq(src.join(bar_before), dst.join(bar_after)).unwrap());
 }
 
 fn file_paths_sorted(root: &Path) -> Vec<PathBuf> {
@@ -46,3 +50,39 @@ fn file_paths_sorted(root: &Path) -> Vec<PathBuf> {
     paths.sort();
     paths
 }
+
+fn files_eq<P: AsRef<Path>>(path_a: P, path_b: P) -> io::Result<bool> {
+    const CHUNK_SIZE: usize = 8;
+
+    let path_a = path_a.as_ref();
+    let path_b = path_b.as_ref();
+
+    let size_a = fs::metadata(path_a)?.len();
+    let size_b = fs::metadata(path_b)?.len();
+    if size_a != size_b {
+        return Ok(false);
+    }
+
+    let mut file_a = File::open(path_a)?;
+    let mut file_b = File::open(path_b)?;
+    let mut buff_a = [0; CHUNK_SIZE];
+    let mut buff_b = [0; CHUNK_SIZE];
+    loop {
+        let n_a = file_a.read(&mut buff_a)?;
+        let n_b = file_b.read(&mut buff_b)?;
+
+        let chunk_a = &buff_a[..n_a];
+        let chunk_b = &buff_b[..n_b];
+
+        if n_a != n_b {
+            return Ok(false);
+        }
+        if chunk_a != chunk_b {
+            return Ok(false);
+        }
+        if n_a == 0 {
+            assert_eq!(n_b, 0);
+            return Ok(true);
+        }
+    }
+}