diff --git a/app/src/main/java/com/piotrwilczek/testcoverage/Calculator.kt b/app/src/main/java/com/piotrwilczek/testcoverage/Calculator.kt
index 0979097..a6bd0e6 100644
--- a/app/src/main/java/com/piotrwilczek/testcoverage/Calculator.kt
+++ b/app/src/main/java/com/piotrwilczek/testcoverage/Calculator.kt
@@ -4,4 +4,6 @@ class Calculator {
     fun add(x: Int, y: Int) = x + y
 
     fun multiply(x: Int, y: Int) = x * y
+
+    fun minus(x: Int, y: Int) = x - y
 }
diff --git a/app/src/test/java/com/piotrwilczek/testcoverage/CalculatorTest.kt b/app/src/test/java/com/piotrwilczek/testcoverage/CalculatorTest.kt
index 34c0881..cb719bd 100644
--- a/app/src/test/java/com/piotrwilczek/testcoverage/CalculatorTest.kt
+++ b/app/src/test/java/com/piotrwilczek/testcoverage/CalculatorTest.kt
@@ -8,4 +8,9 @@ class CalculatorTest {
     fun addition() {
         assertEquals(4, Calculator().add(2, 2))
     }
+
+    @Test
+    fun minus() {
+        assertEquals(0, Calculator().minus(2, 2))
+    }
 }