surf: test serialization of tree

Confirm that the serialization of `source::Tree` has the expected
output.

Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett

radicle-surf/t/src/lib.rs

@@ -6,3 +6,6 @@ mod git;
 
 #[cfg(test)]
 mod file_system;
+
+#[cfg(test)]
+mod source;

radicle-surf/t/src/source.rs

@@ -0,0 +1,39 @@
+use std::path::Path;
+
+use git_ref_format::refname;
+use radicle_surf::{git::Repository, source};
+use serde_json::json;
+
+const GIT_PLATINUM: &str = "../data/git-platinum";
+
+#[test]
+fn tree_serialization() {
+    let repo = Repository::open(GIT_PLATINUM).unwrap();
+    let tree = source::Tree::new(
+        &repo,
+        &refname!("refs/heads/master"),
+        Some(&Path::new("src")),
+    )
+    .unwrap();
+
+    let expected = json!({
+      "entries": [
+        {
+          "kind": "blob",
+          "lastCommit": null,
+          "name": "Eval.hs",
+          "path": "src/Eval.hs"
+        },
+        {
+          "kind": "blob",
+          "lastCommit": null,
+          "name": "memory.rs",
+          "path": "src/memory.rs"
+        }
+      ],
+      "lastCommit": null,
+      "name": "src",
+      "path": "src"
+    });
+    assert_eq!(serde_json::to_value(tree).unwrap(), expected)
+}