Prior to this commit, the longValue() in HeaderResultMatchers added the
expected response header name to generated assertion failure messages;
however, both string() methods did not. This made it more difficult to
analyze the cause of failed tests.
Furthermore, while investigating a solution for this issue it became
apparent that longValue() throws a NullPointerException if the response
does not contain the specified header.
This commit addresses these issues as follows:
- All methods in HeaderResultMatchers now include the response header
name in generated assertion failure messages.
- HeaderResultMatchers.longValue() now avoids NullPointerExceptions by
explicitly asserting that the response contains the specified header.
- The unit tests in HeaderAssertionTests have been expanded to test
most foreseeable use cases.
Issue: SPR-10659
d5a5a4894f