AlmostExhaustiveTestParameter
Prefer an exhaustive @TestParameter with an assumption to filter out specific enum values, so newly added enum values are automatically tested

The problem

When using TestParameterInjector to test all values of an enum except one (or, for proto3 enums, all declared values except one alongside the synthetic UNRECOGNIZED value), prefer an implicit @TestParameter combined with a TruthJUnit.assume() (or JUnit Assume.assumeFalse()) statement in the test method body over listing every included value explicitly.

With an explicit list of included values, any new value added to the enum in the future (for example, a new AVIF constant added to ImageFormat) is silently omitted from the test. Using an implicit @TestParameter with an assumption makes the exclusion self-documenting and ensures that newly added enum values are automatically tested. (Small enums with fewer than 4 included values are ignored.)

@Test
public void decode(
    @TestParameter({"PNG", "JPEG", "GIF", "WEBP"}) ImageFormat format) {
  assertThat(canDecode(format)).isTrue();
}

@Test
public void decode(@TestParameter ImageFormat format) {
  assume().that(format).isNotEqualTo(ImageFormat.UNKNOWN);
  assertThat(canDecode(format)).isTrue();
}

For proto3 enums, excluding a sentinel value such as IMAGE_FORMAT_UNSPECIFIED along with the synthetic UNRECOGNIZED constant can use isNoneOf:

@Test
public void decode(@TestParameter ImageFormat format) {
  assume()
      .that(format)
      .isNoneOf(ImageFormat.IMAGE_FORMAT_UNSPECIFIED, ImageFormat.UNRECOGNIZED);
  assertThat(canDecode(format)).isTrue();
}

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("AlmostExhaustiveTestParameter") to the enclosing element.