Enhance syntax of parameterized_test decorator

docs/advanced.rst

@@ -302,12 +302,11 @@ Depending on that value, the test is set up differently:
 
 If you have already gone through the `tutorial <tutorial.html>`__, this test can be easily understood.
 The new bit here is the ``@parameterized_test`` decorator of the ``MatrixVectorTest`` class.
-This decorator takes as argument an iterable of either sequence (i.e., lists, tuples etc.) or mapping types (i.e., dictionaries).
-Each of this iterable's elements corresponds to the arguments that will be used to instantiate the decorated test each time.
-In the example shown, the test will instantiated twice, once passing ``variant`` as ``MPI`` and a second time with ``variant`` passed as ``OpenMP``.
+This decorator takes an arbitrary number of arguments, which are either of a sequence type (i.e., list, tuple etc.) or of a mapping type (i.e., dictionary).
+Each of the decorator's arguments corresponds to the constructor arguments of the decorated test that will be used to instantiate it.
+In the example shown, the test will be instantiated twice, once passing ``variant`` as ``MPI`` and a second time with ``variant`` passed as ``OpenMP``.
 The framework will try to generate unique names for the generated tests by stringifying the arguments passed to the test's constructor:
 
-
 .. code-block:: none
 
    Command line: ./bin/reframe -C tutorial/config/settings.py -c tutorial/advanced/advanced_example8.py -l
@@ -336,14 +335,14 @@ The dictionaries will be converted to keyword arguments and passed to the constr
 
 .. code-block:: python
 
-   @rfm.parameterized_test([{'variant': 'MPI'}, {'variant': 'OpenMP'}])
+   @rfm.parameterized_test({'variant': 'MPI'}, {'variant': 'OpenMP'})
 
 
 Another way, which is quite useful if you want to generate lots of different tests at the same time, is to use either `list comprehensions <https://docs.python.org/3.6/tutorial/datastructures.html#list-comprehensions>`__ or `generator expressions <https://www.python.org/dev/peps/pep-0289/>`__ for specifying the different test instantiations:
 
 .. code-block:: python
 
-   @rfm.parameterized_test((variant,) for variant in ['MPI', 'OpenMP'])
+   @rfm.parameterized_test(*([variant] for variant in ['MPI', 'OpenMP']))
 
 
 .. note::

reframe/core/decorators.py

@@ -57,23 +57,23 @@ def simple_test(cls):
     return cls
 
 
-def parameterized_test(inst=[]):
+def parameterized_test(*inst):
     """Class decorator for registering multiple instantiations of a test class.
 
    The decorated class must derive from
-   :class:`reframe.core.pipeline.RegressionTest`.  This decorator is also
+   :class:`reframe.core.pipeline.RegressionTest`. This decorator is also
    available directly under the :mod:`reframe` module.
 
-   :arg inst: An iterable of the argument lists of the difference
-              instantiations.  Instantiation arguments may also be passed as
-              keyword dictionaries.
+   :arg inst: The different instantiations of the test. Each instantiation
+        argument may be either a sequence or a mapping.
 
    .. versionadded:: 2.13
 
    .. note::
 
       This decorator does not instantiate any test.  It only registers them.
       The actual instantiation happens during the loading phase of the test.
+
     """
     def _do_register(cls):
         _validate_test(cls)

tutorial/advanced/advanced_example8.py

@@ -2,7 +2,7 @@
 import reframe.utility.sanity as sn
 
 
-@rfm.parameterized_test([('MPI',), ('OpenMP',)])
+@rfm.parameterized_test(['MPI'], ['OpenMP'])
 class MatrixVectorTest(rfm.RegressionTest):
     def __init__(self, variant):
         super().__init__()

unittests/resources/checks_unlisted/good.py

@@ -8,7 +8,7 @@
 from reframe.core.pipeline import RegressionTest
 
 
-@rfm.parameterized_test((x, y) for x in range(3) for y in range(2))
+@rfm.parameterized_test(*((x, y) for x in range(3) for y in range(2)))
 class MyBaseTest(RegressionTest):
     def __init__(self, a, b):
         super().__init__()
@@ -26,7 +26,7 @@ def __repr__(self):
         return 'MyBaseTest(%s, %s)' % (self.a, self.b)
 
 
-@rfm.parameterized_test({'a': x, 'b': y} for x in range(3) for y in range(2))
+@rfm.parameterized_test(*({'a': x, 'b': y} for x in range(3) for y in range(2)))
 class AnotherBaseTest(RegressionTest):
     def __init__(self, a, b):
         super().__init__()

unittests/resources/checks_unlisted/mixed.py

@@ -4,7 +4,7 @@
 from reframe.core.pipeline import RegressionTest
 
 
-@deco.parameterized_test((x, y) for x in range(3) for y in range(2))
+@deco.parameterized_test(*((x, y) for x in range(3) for y in range(2)))
 class MyBaseTest(RegressionTest):
     def __init__(self, a, b):
         super().__init__()