anchor.diff:                           (num-platforms 'cl-uint)
                            (devices 'cl-device-id)
                            (num-devices 'cl-uint)
  +                         (properties 'cl-context-properties 3)
                            (errcode-ret 'cl-int))
       (is +cl-success+ (cl-get-platform-ids 1 platforms num-platforms))
       (let ((platform (mem-aref platforms 'cl-platform-id)))
  
positive.code:                                (null-pointer)
                                 (null-pointer)
                                 (null-pointer)))
          (let ((context (cl-create-context (null-pointer)
                                            1
                                            devices
  
negative.code:                                          0
                                           (null-pointer)
                                           (null-pointer)
                                           (null-pointer)))
          (setf (mem-aref errcode-ret 'cl-int) +cl-success+)
          (setf (mem-aref properties 'cl-context-properties 0) +cl-context-platform+)
          (setf (mem-aref properties 'cl-platform-id 1) platform)
          (setf (mem-aref properties 'cl-context-properties 2) 0)
          (let ((context (cl-create-context-from-type properties
                                                      +cl-device-type-default+
                                                      (null-pointer)
                                                      (null-pointer)
                                                      errcode-ret)))
            (is +cl-success+ (mem-aref errcode-ret 'cl-int))
            (ok context)))
        (subtest "clRetainContext"
          (is +cl-invalid-context+ (cl-retain-context (null-pointer))))
        (subtest "clReleaseContext"
  