diff --git a/test/possum_test/did_test.gleam b/test/possum_test/did_test.gleam
new file mode 100644
index 0000000..41ec437
--- /dev/null
+++ b/test/possum_test/did_test.gleam
@@ -0,0 +1,58 @@
+import gleam/list
+import possum/did
+
+pub fn parse_test() -> Nil {
+  let assert Ok(_) =
+    "did:plc:ewvi7nxzyoun6zhxrhs64oiz"
+    |> did.parse
+
+  let assert Ok(_) =
+    "did:plc:ewvi7nxzyoun6zhxrhs64oiz"
+    |> did.parse
+
+  let assert Ok(_) =
+    "did:web:user.example.com"
+    |> did.parse
+
+  // valid identifier syntax, invalid method
+  let assert Error(did.InvalidDidMethod(_)) =
+    list.try_fold(
+      [
+        "did:method:val:two",
+        "did:m:v",
+        "did:method::::val",
+        "did:method:-:_:.",
+        "did:key:zQ3shZc2QzApp2oymGvQbzP8eKheVshBHbU4ZYjeXqwSKEn6N",
+      ],
+      Nil,
+      fn(_, item) {
+        case did.parse(item) {
+          Ok(_) -> Ok(Nil)
+          Error(err) -> Error(err)
+        }
+      },
+    )
+
+  // invalid identifier syntax
+  let assert Error(did.InvalidFormat(_)) =
+    list.try_fold(
+      [
+        "did:METHOD:val",
+        "did:m123:val",
+        "DID:method:val",
+        "did:method:",
+        "did:method:val/two",
+        "did:method:val?two",
+        "did:method:val#two",
+      ],
+      Nil,
+      fn(_, item) {
+        case did.parse(item) {
+          Ok(_) -> Ok(Nil)
+          Error(err) -> Error(err)
+        }
+      },
+    )
+
+  Nil
+}