Spring ReflectionTestUtils does not set primitive data type field

Question

I use ReflectionTestUtils to set int field in my service class to test the class. My service class like:

@Service
public class SampleService {

    @Value("${app.count}")
    private int count;

    @Value("${app.countStr}")
    private String countStr;

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public String getCountStr() {
        return countStr;
    }

    public void setCountStr(String countStr) {
        this.countStr = countStr;
    }

    @PostConstruct
    public int demoMethod() {
        return count + Integer.parseInt(countStr);
    }
}

and test class is like:

@RunWith(SpringRunner.class)
public class SampleServiceTest {

    @Autowired
    private SampleService sampleService;

    @TestConfiguration
    static class SampleServiceTestConfig {

        @Bean
        public SampleService sampleService() {
            return new SampleService();
        }
    }

    @Before
    public void init() {
        ReflectionTestUtils.setField(sampleService, "count", new Integer(100));
        ReflectionTestUtils.setField(sampleService, "countStr", 100);
    }

    @Test
    public void testDemoMethod() {
        int a  = sampleService.demoMethod();
        Assert.assertTrue(a == 200);
    }
}

While I run this test case it gives below error:

Caused by: java.lang.NumberFormatException: For input string: "${app.count}"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:569)
    at java.lang.Integer.valueOf(Integer.java:766)
    at org.springframework.util.NumberUtils.parseNumber(NumberUtils.java:210)
    at org.springframework.beans.propertyeditors.CustomNumberEditor.setAsText(CustomNumberEditor.java:115)
    at org.springframework.beans.TypeConverterDelegate.doConvertTextValue(TypeConverterDelegate.java:466)
    at org.springframework.beans.TypeConverterDelegate.doConvertValue(TypeConverterDelegate.java:439)
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:192)
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:117)
    at org.springframework.beans.TypeConverterSupport.doConvert(TypeConverterSupport.java:70)
    ... 47 more

Why ReflectionTestUtils try set string value in the field?

I put 2 fields, one is an integer and another is a string for testing purpose.

You can find source code here .

Please have look and suggest a workaround for the same.

Answer 1

Your problem is that the method annotated with @Before is invoked after that the spring context was initialized and that the service was injected by Spring in your test class.
Which means that these two fields :

@Value("${app.count}")
private int count;

@Value("${app.countStr}")
private String countStr;

will have as value the value defined in their @Value values.
String countStr can be valued with the "${app.countStr}" String (even it it makes no sense).
But int count cannot be valued with the "${app.count}" String as "${app.count}" cannot be converted into an int value .
Whereas the thrown exception as Integer.parseInt("${app.count}") is invoked :

Caused by: java.lang.NumberFormatException: For input string: "${app.count}"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:569)

To address this issue, use @TestPropertySource as suggested by Nisheeth Shah to provide the value for the properties at the suitable time.

As a general advise, limit the reflection use. It is checked only at runtime and that is often more opaque.

Answer 2

While testing, you have to provide properties source. If you don't add properties, it will inject the value inside @Value in the variable. In your case, it tries to add the string in the integer that gives NumberFormatException . Try adding as below:

@RunWith(SpringRunner.class)
@TestPropertySource(properties = {"app.count=1", "app.countStr=sampleString"})
public class SampleServiceTest{...}

I hope it helps.

As you are using @Autowired , before ReflectionTestUtils it tries to add the value inside @Value .