add nar tests

tests/nar.rs

@@ -0,0 +1,26 @@
+use crate::common::HELLO_PATH;
+use nix_compat::nixbase32;
+use nixcp::make_nar::MakeNar;
+use nixcp::path_info::PathInfo;
+use sha2::Digest;
+use tokio::io::AsyncReadExt;
+
+mod common;
+
+#[tokio::test]
+async fn nar_size_and_hash() {
+    let ctx = common::context();
+    let path_info = PathInfo::from_path(HELLO_PATH, &ctx.store).await.unwrap();
+
+    let mut nar = MakeNar::new(&path_info, ctx.store).unwrap();
+    let mut reader = nar.compress_and_hash().unwrap();
+    let mut buf = Vec::new();
+    reader.read_to_end(&mut buf).await.unwrap();
+    drop(reader);
+
+    assert_eq!(nar.nar_size, 234680);
+
+    let nar_hash = nar.nar_hasher.finalize();
+    let real_nar_hash = "08za7nnjda8kpdsd73v3mhykjvp0rsmskwsr37winhmzgm6iw79w";
+    assert_eq!(nixbase32::encode(nar_hash.as_slice()), real_nar_hash);
+}