diff --git a/app/src/test/BMICalculatorTest.kt b/app/src/test/BMICalculatorTest.kt
new file mode 100644
index 0000000..54be5de
--- /dev/null
+++ b/app/src/test/BMICalculatorTest.kt
@@ -0,0 +1,63 @@
+package com.example.tiptime
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class BMICalculatorTest {
+    // Test untuk perhitungan BMI dengan unit Metric
+    @Test
+    fun calculateBMI_metricUnits_correctCalculation() {
+        val result = calculateBMI(170.0, 65.0, false)
+        assertEquals("22.5", result)
+    }
+
+    // Test untuk perhitungan BMI dengan unit USC (Imperial)
+    @Test
+    fun calculateBMI_uscUnits_correctCalculation() {
+        val result = calculateBMI(68.0, 150.0, true)
+        // Rumus: 703 * (150 / (68^2)) = 22.8
+        assertEquals("22.8", result)
+    }
+
+    // Test jika input tinggi atau berat = 0 → hasil harus "0.0"
+    @Test
+    fun calculateBMI_zeroInput_returnsZero() {
+        val result = calculateBMI(0.0, 0.0, false)
+        assertEquals("0.0", result)
+    }
+
+    // Test kategori BMI untuk underweight
+    @Test
+    fun calculateBMICategory_underweight_returnsUnderweight() {
+        val result = calculateBMICategory("17.5")
+        assertEquals("Underweight", result)
+    }
+
+    // Test kategori BMI untuk normal weight
+    @Test
+    fun calculateBMICategory_normal_returnsNormal() {
+        val result = calculateBMICategory("22.0")
+        assertEquals("Normal weight", result)
+    }
+
+    // Test kategori BMI untuk overweight
+    @Test
+    fun calculateBMICategory_overweight_returnsOverweight() {
+        val result = calculateBMICategory("27.0")
+        assertEquals("Overweight", result)
+    }
+
+    // Test kategori BMI untuk obese
+    @Test
+    fun calculateBMICategory_obese_returnsObese() {
+        val result = calculateBMICategory("32.0")
+        assertEquals("Obese", result)
+    }
+
+    // Test input tidak valid (string bukan angka)
+    @Test
+    fun calculateBMICategory_invalidInput_returnsTidakDiketahui() {
+        val result = calculateBMICategory("abc")
+        assertEquals("Underweight", result) // default 0.0 masuk ke underweight
+    }
+}
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