diff --git a/tests/format.rs b/tests/format.rs
new file mode 100644
index 0000000..ab35494
--- /dev/null
+++ b/tests/format.rs
@@ -0,0 +1,23 @@
+use numf::format::*;
+
+#[test]
+fn format() {
+    let options = FormatOptions::default();
+    assert_eq!(Format::Dec.format(1337, &options), "1337");
+    assert_eq!(Format::Dec.format(u128::MAX, &options), format!("{}", u128::MAX));
+
+    assert_eq!(Format::Hex.format(0x1337, &options), "1337");
+    assert_eq!(Format::Hex.format(u128::MAX, &options), format!("{:X}", u128::MAX));
+
+    assert_eq!(Format::Bin.format(0b1010001001010010010100111, &options), "1010001001010010010100111");
+    assert_eq!(Format::Bin.format(u128::MAX, &options), format!("{:b}", u128::MAX));
+
+    assert_eq!(Format::Octal.format(0o13377331, &options), "13377331");
+    assert_eq!(Format::Octal.format(u128::MAX, &options), format!("{:o}", u128::MAX));
+
+    assert_eq!(Format::Base32.format(0x41414242, &options), "IFAUEQQ=");
+    assert_eq!(Format::Base32.format(0x4141414141414141, &options), "IFAUCQKBIFAUC===");
+
+    assert_eq!(Format::Base64.format(0x41414242, &options), "QUFCQg==");
+    assert_eq!(Format::Base64.format(0x4141414141414141, &options), "QUFBQUFBQUE=");
+}