diff --git a/src/extract.rs b/src/extract.rs
index b389728..0244082 100644
--- a/src/extract.rs
+++ b/src/extract.rs
@@ -18,3 +18,48 @@ pub(crate) fn extract_links(md: &str) -> HashSet<Url> {
 
     links
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use std::iter::FromIterator;
+
+    #[test]
+    fn test_extract_markdown_links() {
+        let md = "This is [a test](https://endler.dev).";
+        let links = extract_links(md);
+        assert_eq!(
+            links,
+            HashSet::from_iter([Url::parse("https://endler.dev").unwrap()].iter().cloned())
+        )
+    }
+
+    #[test]
+    fn test_skip_markdown_anchors() {
+        let md = "This is [a test](#lol).";
+        let links = extract_links(md);
+        assert_eq!(links, HashSet::new())
+    }
+
+    #[test]
+    fn test_skip_markdown_iternal_urls() {
+        let md = "This is [a test](./internal).";
+        let links = extract_links(md);
+        assert_eq!(links, HashSet::new())
+    }
+
+    #[test]
+    fn test_non_markdown_links() {
+        let md = "https://endler.dev and https://hello-rust.show/foo/bar?lol=1";
+        let links = extract_links(md);
+        let expected = HashSet::from_iter(
+            [
+                Url::parse("https://endler.dev").unwrap(),
+                Url::parse("https://hello-rust.show/foo/bar?lol=1").unwrap(),
+            ]
+            .iter()
+            .cloned(),
+        );
+        assert_eq!(links, expected)
+    }
+}