feat(tvix/nix-compat/nar/reader): add tests r/6856

Change-Id: If0abaf74a3b7d201af8972e54e3e34b20b8c0bc4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9764
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>

5 files changed, 122 insertions, 0 deletions

diff --git a/tvix/nix-compat/src/nar/reader/mod.rs b/tvix/nix-compat/src/nar/reader/mod.rs
index e0b2e1c84574..09af41866508 100644
--- a/tvix/nix-compat/src/nar/reader/mod.rs
+++ b/tvix/nix-compat/src/nar/reader/mod.rs
@@ -14,6 +14,8 @@ use std::io::{
 use crate::nar::wire;
 
 mod read;
+#[cfg(test)]
+mod test;
 
 pub type Reader<'a> = dyn Read + Send + 'a;
 
diff --git a/tvix/nix-compat/src/nar/reader/test.rs b/tvix/nix-compat/src/nar/reader/test.rs
new file mode 100644
index 000000000000..fd0d6a9f5afd
--- /dev/null
+++ b/tvix/nix-compat/src/nar/reader/test.rs
@@ -0,0 +1,120 @@
+use std::io::Read;
+
+use crate::nar;
+
+#[test]
+fn symlink() {
+    let mut f = std::io::Cursor::new(include_bytes!("../tests/symlink.nar"));
+    let node = nar::reader::open(&mut f).unwrap();
+
+    match node {
+        nar::reader::Node::Symlink { target } => {
+            assert_eq!(
+                &b"/nix/store/somewhereelse"[..],
+                &target,
+                "target must match"
+            );
+        }
+        _ => panic!("unexpected type"),
+    }
+}
+
+#[test]
+fn file() {
+    let mut f = std::io::Cursor::new(include_bytes!("../tests/helloworld.nar"));
+    let node = nar::reader::open(&mut f).unwrap();
+
+    match node {
+        nar::reader::Node::File {
+            executable,
+            mut reader,
+        } => {
+            assert!(!executable);
+            let mut buf = vec![];
+            reader.read_to_end(&mut buf).expect("read must succeed");
+            assert_eq!(&b"Hello World!"[..], &buf);
+        }
+        _ => panic!("unexpected type"),
+    }
+}
+
+#[test]
+fn complicated() {
+    let mut f = std::io::Cursor::new(include_bytes!("../tests/complicated.nar"));
+    let node = nar::reader::open(&mut f).unwrap();
+
+    match node {
+        nar::reader::Node::Directory(mut dir_reader) => {
+            // first entry is .keep, an empty regular file.
+            let entry = dir_reader
+                .next()
+                .expect("next must succeed")
+                .expect("must be some");
+
+            assert_eq!(&b".keep"[..], &entry.name);
+
+            match entry.node {
+                nar::reader::Node::File {
+                    executable,
+                    mut reader,
+                } => {
+                    assert!(!executable);
+                    assert_eq!(reader.read(&mut [0]).unwrap(), 0);
+                }
+                _ => panic!("unexpected type for .keep"),
+            }
+
+            // second entry is aa, a symlink to /nix/store/somewhereelse
+            let entry = dir_reader
+                .next()
+                .expect("next must be some")
+                .expect("must be some");
+
+            assert_eq!(&b"aa"[..], &entry.name);
+
+            match entry.node {
+                nar::reader::Node::Symlink { target } => {
+                    assert_eq!(&b"/nix/store/somewhereelse"[..], &target);
+                }
+                _ => panic!("unexpected type for aa"),
+            }
+
+            // third entry is a directory called "keep"
+            let entry = dir_reader
+                .next()
+                .expect("next must be some")
+                .expect("must be some");
+
+            assert_eq!(&b"keep"[..], &entry.name);
+
+            match entry.node {
+                nar::reader::Node::Directory(mut subdir_reader) => {
+                    // first entry is .keep, an empty regular file.
+                    let entry = subdir_reader
+                        .next()
+                        .expect("next must succeed")
+                        .expect("must be some");
+
+                    // … it contains a single .keep, an empty regular file.
+                    assert_eq!(&b".keep"[..], &entry.name);
+
+                    match entry.node {
+                        nar::reader::Node::File {
+                            executable,
+                            mut reader,
+                        } => {
+                            assert!(!executable);
+                            assert_eq!(reader.read(&mut [0]).unwrap(), 0);
+                        }
+                        _ => panic!("unexpected type for keep/.keep"),
+                    }
+                }
+                _ => panic!("unexpected type for keep/.keep"),
+            }
+
+            // reading more entries yields None (and we actually must read until this)
+            assert!(dir_reader.next().expect("must succeed").is_none());
+        }
+        _ => panic!("unexpected type"),
+    }
+}
diff --git a/tvix/nix-compat/src/nar/tests/complicated.nar b/tvix/nix-compat/src/nar/tests/complicated.nar
new file mode 100644
index 000000000000..6a137f5fbb6b
--- /dev/null
+++ b/tvix/nix-compat/src/nar/tests/complicated.nar
Binary files differdiff --git a/tvix/nix-compat/src/nar/tests/helloworld.nar b/tvix/nix-compat/src/nar/tests/helloworld.nar
new file mode 100644
index 000000000000..2e1268115205
--- /dev/null
+++ b/tvix/nix-compat/src/nar/tests/helloworld.nar
Binary files differdiff --git a/tvix/nix-compat/src/nar/tests/symlink.nar b/tvix/nix-compat/src/nar/tests/symlink.nar
new file mode 100644
index 000000000000..7990e4ad5bc2
--- /dev/null
+++ b/tvix/nix-compat/src/nar/tests/symlink.nar
Binary files differ