diff --git a/converter/converter_test.go b/converter/converter_test.go
new file mode 100644
index 0000000..5661a7e
--- /dev/null
+++ b/converter/converter_test.go
@@ -0,0 +1,61 @@
+package converter
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestConvert(t *testing.T) {
+	result, err := Convert("50aa", "km")
+	if err == nil {
+		t.Log("should be error")
+		t.Fail()
+	}
+
+	result, err = Convert("aami", "km")
+	if err == nil {
+		t.Log("should be error")
+		t.Fail()
+	}
+
+	result, err = Convert("50mi", "aa")
+	if err == nil {
+		t.Log("should be error")
+		t.Fail()
+	}
+
+	result, err = Convert("50mi", "km")
+	if err != nil {
+		t.Log("error should be nil")
+		t.Fail()
+	}
+	if !strings.HasSuffix(result, "km") {
+		t.Log("wrong unit")
+		t.Fail()
+	}
+
+	convTests := []struct{ input, unit1, unit2 string }{
+		{"50.00", "mi", "km"},
+		{"50.00", "ft", "m"},
+	}
+
+	for _, c := range convTests {
+		input := c.input + c.unit1
+		conv1, err := Convert(input, c.unit2)
+		if err != nil {
+			t.Log("error should be nil")
+			t.Fail()
+		}
+		conv2, err := Convert(conv1, c.unit1)
+		if err != nil {
+			t.Log("error should be nil")
+			t.Fail()
+		}
+		if input != conv2 {
+			t.Log("Conversion error", input, conv2)
+			t.Fail()
+		}
+
+	}
+
+}