Assert that exception message contains one of multiple strings

[sebthom]

I have the case where I want assert that the thrown exception contains one of several possible strings in the error message.

What is the best way to achieve something like this:

assertThatThrownBy(() -> {
  /* code to test */
})
.isInstanceOf(CertPathValidatorException.class)
.hasMessageContaining(
   either( // this is pseudo code
     "could not be determined", 
     "could not determine revocation status", 
     "revocation status check failed"
   )
)

Another case would be

assertThatThrownBy(() -> {
  /* code to test */
})
.isInstanceOf(CertPathValidatorException.class)
.hasMessageContaining(
   // pseudo code
   System.getProperty("java.vm.vendor").contains("IBM") 
     ? "has been revoked for an unspecified reason"
     : either(
         "could not determine revocation status", 
         "revocation status check failed"
       )
)

[scordio]

hasMessageMatching might be an alternative for some cases. Not the best readability, though.

Another option that can be used is extracting(Function, InstanceOfAssertFactory):

assertThatThrownBy(() -> {
  /* code to test */
})
  .isInstanceOf(CertPathValidatorException.class)
  .extracting(Throwable::getMessage, as(InstanceOfAssertFactories.STRING))
  .containsAnyOf(
    "could not be determined",
    "could not determine revocation status",
    "revocation status check failed"
  );

We could add a navigational method to get the message as a string assertion, that would shorten a bit the extracting line. It would allow writing something like:

assertThatThrownBy(() -> {
  /* code to test */
})
  .isInstanceOf(CertPathValidatorException.class)
  .message() // returns StringAssert
  .containsAnyOf(
    "could not be determined", 
    "could not determine revocation status", 
    "revocation status check failed"
  );

Readability-wise, I'm not sure what is the best way to handle the conditional string under System.getProperty("java.vm.vendor").contains("IBM"). Maybe you could declare the containsAnyOf input outside the assertion as a CharSequence array, which would have one element if the condition is true or two elements if the condition is false:

CharSequence[] messages = System.getProperty("java.vm.vendor").contains("IBM")
  ? new CharSequence[] { "has been revoked for an unspecified reason" }
  : new CharSequence[] { "could not determine revocation status", "revocation status check failed" };

assertThatThrownBy(() -> {
  /* code to test */
})
  .isInstanceOf(CertPathValidatorException.class)
  .extracting(Throwable::getMessage, as(InstanceOfAssertFactories.STRING))
  .containsAnyOf(messages);

[sebthom]

Thanks your quick response! Very valuable information!

I am using your last suggestion now.

It would be nice if the message() shortcut for .extracting(Throwable::getMessage, as(InstanceOfAssertFactories.STRING)) you mentioned could be added to AbstractThrowableAssert.

[scordio]

Thanks for raising #2378!