/category:[filter Use the specified filter to select tests to run based on the test category of each test. You can use the ...

  /category:[filter]                Use the specified filter to select tests 
                                    to run based on the test category of each
                                    test. 
                                    You can use the logical operators 
                                    and ! to construct your filter, or you 
                                    can use logical operators | and ! to 
                                    filter the tests.
                                    Examples:
                                    /category:Priority1 
                                       (any tests with category: Priority1)
                                    /category:"Priority1&MyTests" 
                                       (tests that must have multiple 
                                        categories: Priority1 and MyTests)
                                    /category:"Priority1|MyTests" 
                                       (all tests from multiple 
                                        categories: Priority 1 or MyTests)
                                    /category:"Priority1&!MyTests" 
                                       (filter out tests: Priority1 tests 
                                         that do not have a test category 
                                         of MyTests)