kunit: tool: update test counts summary line format

Before:
> Testing complete. Passed: 137, Failed: 0, Crashed: 0, Skipped: 36, Errors: 0

After:
> Testing complete. Ran 173 tests: passed: 137, skipped: 36

Even with our current set of statuses, the output is a bit verbose.
It could get worse in the future if we add more (e.g. timeout, kasan).
Let's only print the relevant ones.

I had previously been sympathetic to the argument that always
printing out all the statuses would make it easier to parse results.
But now we have commit acd8e8407b ("kunit: Print test statistics on
failure"), there are test counts printed out in the raw output.
We don't currently print out an overall total across all suites, but it
would be easy to add, if we see a need for that.

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Co-developed-by: David Gow <davidgow@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit_parser.py

@@ -94,11 +94,11 @@ class TestCounts:
 	def __str__(self) -> str:
 		"""Returns the string representation of a TestCounts object.
 		"""
-		return ('Passed: ' + str(self.passed) +
-			', Failed: ' + str(self.failed) +
-			', Crashed: ' + str(self.crashed) +
-			', Skipped: ' + str(self.skipped) +
-			', Errors: ' + str(self.errors))
+		statuses = [('passed', self.passed), ('failed', self.failed),
+			('crashed', self.crashed), ('skipped', self.skipped),
+			('errors', self.errors)]
+		return f'Ran {self.total()} tests: ' + \
+			', '.join(f'{s}: {n}' for s, n in statuses if n > 0)
 
 	def total(self) -> int:
 		"""Returns the total number of test cases within a test