[wip] unit tests for file module

- testing/coverage for module

src/file/mod.rs

@@ -13,6 +13,8 @@ use log::{debug, warn};
 pub use uploading::Uploading;
 
 /// how many bytes to hash at once (default: 4 MiB)
+///
+/// size must never exceed 2 EiB
 const HASH_CHUNK_SIZE: usize = 4 * 1024 * 1024;
 
 /// compute hash for a file given its path.
@@ -45,7 +47,6 @@ fn compute_hash(path: &Path, size: u64, mut on_progress: impl FnMut(u64)) -> cra
         }
         hasher.update(&buffer[..n]);
 
-        // `buf` size must be < 2 EiB
         bytes_read += n as u64;
         on_progress(n as u64);
     }
@@ -124,6 +125,8 @@ pub trait FileTrait {
 
 #[cfg(test)]
 mod tests {
+    use tempfile::TempDir;
+
     use crate::test_util::{
         create_file,
         data::{DATA_LENGTHS_BAD, HASHES_STD_BAD, HASHES_STD_GOOD, cases, cases_with},
@@ -146,6 +149,28 @@ mod tests {
         }
     }
 
+    #[test]
+    fn compute_hash_nonexistent_file() {
+        let nex_path = {
+            // this is deleted at the end of this block, so will stop to exist
+            let nex_file = create_file(&[]);
+            nex_file.path().to_owned()
+        };
+
+        let err = compute_hash(&nex_path, 0, drop).unwrap_err();
+        assert!(matches!(err, crate::Error::StdIo(e) if e.kind() == std::io::ErrorKind::NotFound));
+    }
+
+    #[test]
+    fn compute_hash_directory() {
+        let dir = TempDir::new().unwrap();
+
+        let err = compute_hash(dir.path(), 0, drop).unwrap_err();
+        assert!(
+            matches!(err, crate::Error::StdIo(e) if e.kind() == std::io::ErrorKind::IsADirectory)
+        );
+    }
+
     #[test]
     fn hash_size_mismatch() {
         for (content, good_size, bad_size) in cases_with(DATA_LENGTHS_BAD) {