diff --git a/src/utils.test.ts b/src/utils.test.ts
new file mode 100644
index 00000000..a48d0832
--- /dev/null
+++ b/src/utils.test.ts
@@ -0,0 +1,19 @@
+import { isNumberFrom1To100 } from '@/utils.ts';
+import { assertEquals } from 'https://deno.land/std@0.132.0/testing/asserts.ts';
+
+Deno.test('Value is any number from 1 to 100', () => {
+  assertEquals(isNumberFrom1To100('latvia'), false);
+  assertEquals(isNumberFrom1To100(1.5), false);
+  assertEquals(isNumberFrom1To100(Infinity), false);
+  assertEquals(isNumberFrom1To100('Infinity'), false);
+  assertEquals(isNumberFrom1To100('0'), false);
+  assertEquals(isNumberFrom1To100(0), false);
+  assertEquals(isNumberFrom1To100(-1), false);
+  assertEquals(isNumberFrom1To100('-10'), false);
+
+  for (let i = 1; i < 100; i++) {
+    assertEquals(isNumberFrom1To100(String(i)), true);
+  }
+
+  assertEquals(isNumberFrom1To100('1e1'), true);
+});