Add new config tuple cache (renatahodovan#34)

It uses a dictionary of tuples as the underlying data structure,
contrary to the classic config cache that uses a tree.

picire/cache.py

@@ -184,6 +184,50 @@ def _str(p):
         return ''.join(s)
 
 
+@CacheRegistry.register('config-tuple')
+class ConfigTupleCache(OutcomeCache):
+    """
+    This cache associates configurations (i.e., lists of elements) with their
+    test outcomes, using a dictionary of tuples as the underlying data
+    structure.
+    """
+
+    def __init__(self, *, cache_fail=False, evict_after_fail=True):
+        """
+        :param cache_fail: Add configurations with FAIL outcome to the cache.
+        :param evict_after_fail: When a configuration with a FAIL outcome is
+            added to the cache, evict all larger configurations.
+        """
+        # NOTE: evict_after_fail=True should be safe as after a fail is found,
+        # reduction continues from there, generating only even smaller test
+        # cases, and larger tests are never re-tested again.
+        self._cache_fail = cache_fail
+        self._evict_after_fail = evict_after_fail
+        self._container = {}
+
+    def set_test_builder(self, test_builder):
+        pass
+
+    def add(self, config, result):
+        if result is Outcome.PASS or self._cache_fail:
+            self._container[tuple(config)] = result
+
+        if result is Outcome.FAIL and self._evict_after_fail:
+            length = len(config)
+            evicted = [c for c in self._container if len(c) > length]
+            for c in evicted:
+                del self._container[c]
+
+    def lookup(self, config):
+        return self._container.get(tuple(config), None)
+
+    def clear(self):
+        self._container = {}
+
+    def __str__(self):
+        return '{\n%s}' % ''.join(f'\t{c!r}: {r.name!r},\n' for c, r in sorted(self._container.items()))
+
+
 @CacheRegistry.register('content')
 class ContentCache(OutcomeCache):
     """

tests/test_api.py

@@ -85,20 +85,20 @@ def _run_picire(self, interesting, config, expect, granularity, dd, split, subse
     @pytest.mark.parametrize('split, subset_first, subset_iterator, complement_iterator, cache', [
         (picire.splitter.BalancedSplit, True, picire.iterator.forward, picire.iterator.forward, picire.cache.NoCache),
         (picire.splitter.ZellerSplit, True, picire.iterator.forward, picire.iterator.backward, picire.cache.ConfigCache),
-        (picire.splitter.BalancedSplit, False, picire.iterator.backward, picire.iterator.forward, picire.cache.NoCache),
-        (picire.splitter.ZellerSplit, False, picire.iterator.backward, picire.iterator.backward, picire.cache.ConfigCache),
-        (picire.splitter.BalancedSplit, True, picire.iterator.skip, picire.iterator.forward, picire.cache.NoCache),
-        (picire.splitter.ZellerSplit, True, picire.iterator.skip, picire.iterator.backward, picire.cache.ConfigCache),
+        (picire.splitter.BalancedSplit, False, picire.iterator.backward, picire.iterator.forward, picire.cache.ConfigTupleCache),
+        (picire.splitter.ZellerSplit, False, picire.iterator.backward, picire.iterator.backward, picire.cache.NoCache),
+        (picire.splitter.BalancedSplit, True, picire.iterator.skip, picire.iterator.forward, picire.cache.ConfigCache),
+        (picire.splitter.ZellerSplit, True, picire.iterator.skip, picire.iterator.backward, picire.cache.ConfigTupleCache),
     ])
     def test_dd(self, interesting, config, expect, granularity, split, subset_first, subset_iterator, complement_iterator, cache):
         self._run_picire(interesting, config, expect, granularity, picire.DD, split, subset_first, subset_iterator, complement_iterator, cache)
 
     @pytest.mark.parametrize('split, subset_first, subset_iterator, complement_iterator, cache', [
         (picire.splitter.ZellerSplit, False, picire.iterator.forward, picire.iterator.forward, picire.cache.ConfigCache),
-        (picire.splitter.BalancedSplit, False, picire.iterator.forward, picire.iterator.backward, picire.cache.NoCache),
-        (picire.splitter.ZellerSplit, True, picire.iterator.backward, picire.iterator.forward, picire.cache.ConfigCache),
-        (picire.splitter.BalancedSplit, True, picire.iterator.backward, picire.iterator.backward, picire.cache.NoCache),
-        (picire.splitter.ZellerSplit, False, picire.iterator.skip, picire.iterator.forward, picire.cache.ConfigCache),
+        (picire.splitter.BalancedSplit, False, picire.iterator.forward, picire.iterator.backward, picire.cache.ConfigTupleCache),
+        (picire.splitter.ZellerSplit, True, picire.iterator.backward, picire.iterator.forward, picire.cache.NoCache),
+        (picire.splitter.BalancedSplit, True, picire.iterator.backward, picire.iterator.backward, picire.cache.ConfigCache),
+        (picire.splitter.ZellerSplit, False, picire.iterator.skip, picire.iterator.forward, picire.cache.ConfigTupleCache),
         (picire.splitter.BalancedSplit, False, picire.iterator.skip, picire.iterator.backward, picire.cache.NoCache),
     ])
     def test_parallel(self, interesting, config, expect, granularity, split, subset_first, subset_iterator, complement_iterator, cache):

tests/test_cli.py

@@ -52,15 +52,15 @@ def _run_picire(self, test, inp, exp, tmpdir, args):
         ('--split=balanced', '--subset-iterator=forward', '--complement-iterator=forward', '--cache=config'),
         ('--split=zeller', '--subset-iterator=forward', '--complement-iterator=backward', '--cache=content'),
         ('--split=balanced', '--complement-first', '--subset-iterator=backward', '--complement-iterator=forward', '--cache=content-hash'),
-        ('--split=zeller', '--complement-first', '--subset-iterator=backward', '--complement-iterator=backward', '--cache=config', '--cache-fail', '--no-cache-evict-after-fail'),
+        ('--split=zeller', '--complement-first', '--subset-iterator=backward', '--complement-iterator=backward', '--cache=config-tuple', '--cache-fail', '--no-cache-evict-after-fail'),
         ('--split=balanced', '--subset-iterator=skip', '--complement-iterator=forward', '--cache=content', '--cache-fail', '--no-cache-evict-after-fail'),
         ('--split=zeller', '--subset-iterator=skip', '--complement-iterator=backward', '--cache=content-hash', '--cache-fail', '--no-cache-evict-after-fail'),
     ])
     def test_dd(self, test, inp, exp, tmpdir, args_atom, args):
         self._run_picire(test, inp, exp, tmpdir, args_atom + args)
 
     @pytest.mark.parametrize('args', [
-        ('--split=zeller', '--complement-first', '--subset-iterator=forward', '--complement-iterator=forward', '--cache=config'),
+        ('--split=zeller', '--complement-first', '--subset-iterator=forward', '--complement-iterator=forward', '--cache=config-tuple'),
         ('--split=balanced', '--complement-first', '--subset-iterator=forward', '--complement-iterator=backward', '--cache=content'),
         ('--split=zeller', '--subset-iterator=backward', '--complement-iterator=forward', '--cache=content-hash'),
         ('--split=balanced', '--subset-iterator=backward', '--complement-iterator=backward', '--cache=config', '--cache-fail', '--no-cache-evict-after-fail'),