Add "node::extract" test; Remove test objects from git;

.gitignore

@@ -1 +1,3 @@
 /target
+test/
+!test/li.txt

src/node.rs

@@ -319,9 +319,13 @@ mod tests {
     fn from_path() {
         let links = Mutex::new(HashMap::new());
         let node = Node::from_path("test/li.txt", Algorithm::Sha256, &links).unwrap();
-        let FileType::Normal(f) = node.filetype else { panic!() };
+        let FileType::Normal(f) = node.filetype else {
+            panic!()
+        };
         assert_eq!(f.len, 1005);
-        let Checksum::Sha256(sum) = f.checksum else { panic!() };
+        let Checksum::Sha256(sum) = f.checksum else {
+            panic!()
+        };
         let mut s = String::new();
         for c in &sum {
             write!(s, "{c:02x}").unwrap();
@@ -344,8 +348,12 @@ mod tests {
         let fd = std::fs::File::open("test/li.node").unwrap();
         let mut reader = BufReader::new(fd);
         let node = Node::read(&mut reader).unwrap();
-        let FileType::Normal(f) = node.filetype else { panic!() };
-        let Checksum::Sha1(sum) = f.checksum else { panic!() };
+        let FileType::Normal(f) = node.filetype else {
+            panic!()
+        };
+        let Checksum::Sha1(sum) = f.checksum else {
+            panic!()
+        };
         let mut s = String::new();
         for c in &sum {
             write!(s, "{c:02x}").unwrap();
@@ -353,4 +361,13 @@ mod tests {
         assert_eq!(s, "9bf3e5b5efd22f932e100b86c83482787e82a682");
         assert_eq!(LI, f.data);
     }
+
+    #[test]
+    fn extract_file() {
+        let links = Mutex::new(HashMap::new());
+        let node = Node::from_path("test/li.txt", Algorithm::Sha256, &links).unwrap();
+        node.extract(Some("test/output")).unwrap();
+        let f = fs::read_to_string("test/output/test/li.txt").unwrap();
+        assert_eq!(f.as_bytes(), LI);
+    }
 }