diff --git a/app/src/main/java/com/coderabbit/app/calculator/Adder.kt b/app/src/main/java/com/coderabbit/app/calculator/Adder.kt
new file mode 100644
index 0000000..257f267
--- /dev/null
+++ b/app/src/main/java/com/coderabbit/app/calculator/Adder.kt
@@ -0,0 +1,8 @@
+package com.coderabbit.app.calculator
+
+class Adder {
+
+    fun minus(a: Int, b: Int): Int {
+        return a - b
+    }
+}
\ No newline at end of file
diff --git a/app/src/test/java/com/coderabbit/app/calculator/AdderTest.kt b/app/src/test/java/com/coderabbit/app/calculator/AdderTest.kt
new file mode 100644
index 0000000..2877381
--- /dev/null
+++ b/app/src/test/java/com/coderabbit/app/calculator/AdderTest.kt
@@ -0,0 +1,13 @@
+package com.coderabbit.app.calculator
+
+import org.junit.Test
+
+
+class AdderTest {
+
+    @Test
+    fun `test minus function`() {
+        val adder = Adder()
+        assert(adder.minus(5, 3) == 2)
+    }
+}
\ No newline at end of file