@ValueAutoSource

The @ValueAutoSource annotation combines the capabilities of @ValueSource and @AutoSource, providing a more flexible way to generate test arguments. Specifically, it assigns a predefined value to the first parameter and then generates arbitrary values for the remaining parameters.

How to Use

To employ the @ValueAutoSource annotation, add it above your test method and specify the values for the first parameter using the attributes like strings, ints, etc., just as you would with @ValueSource.

Here's an example:

Java

@ParameterizedTest
@ValueAutoSource(strings = {"foo"})
void testMethod(String arg1, String arg2) {
    assertEquals("foo", arg1);
    assertNotEquals(arg1, arg2);
}

Kotlin

@ParameterizedTest
@ValueAutoSource(strings = ["foo"])
fun testMethod(arg1: String, arg2: String) {
    assertEquals("foo", arg1)
    assertNotEquals(arg1, arg2)
}

In this case, arg1 is set to "foo", while arg2 will receive an automatically generated value. The test confirms that arg1 is exactly "foo" and that arg2 is different from arg1.

Compatibility with @Freeze

The @ValueAutoSource annotation is fully compatible with the @Freeze annotation, allowing you to fix certain parameter values while also providing predefined values for others.

Here is how they can work together:

Java

@AllArgsConstructor
@Getter
public class ValueContainer {
    private final String value;
}

Kotlin

class ValueContainer(val value: String)

Java

@ParameterizedTest
@ValueAutoSource(strings = {"foo"})
void testMethod(@Freeze String arg1, String arg2, ValueContainer arg3) {
    assertEquals("foo", arg2);
    assertEquals("foo", arg3.getValue());
}

Kotlin

@ParameterizedTest
@ValueAutoSource(strings = ["foo"])
fun testMethod(@Freeze arg1: String, arg2: String, arg3: ValueContainer) {
    assertEquals("foo", arg2)
    assertEquals("foo", arg3.value)
}

Benefits

1. Combining Fixed and Random Values: @ValueAutoSource allows you to specify certain parameter values while letting AutoParams generate random values for others, offering the best of both worlds.
2. Enhanced Flexibility: This feature grants you more control over test data, making it easier to cover a wide range of scenarios.
3. Reduced Test Complexity: By combining the functionalities of @ValueSource and @AutoSource, you can simplify your test setup, making it easier to read and maintain.

The @ValueAutoSource annotation is a versatile addition to your testing toolkit, giving you greater control over test data while maintaining the benefits of automated random data generation.