BAEL-4321 yaml config to map in pojo demo

spring-boot-modules/spring-boot-properties-3/src/test/java/com/baeldung/boot/properties/controller/TshirtSizeControllerTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.boot.properties.controller;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import com.baeldung.boot.properties.service.SizeConverterService;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class TshirtSizeControllerUnitTest {
+
+    @Mock
+    private SizeConverterService service;
+
+    @InjectMocks
+    private TshirtSizeController tested;
+
+    @Test
+    void whenConvertSize_thenOK() {
+
+        // Given
+        String label = "S";
+        String countryCode = "fr";
+        int result = 36;
+
+        // When
+        when(service.convertSize(label, countryCode)).thenReturn(result);
+        int actual = tested.convertSize(label, countryCode);
+
+        // Then
+        assertEquals(actual, result);
+
+    }
+}