diff --git a/.gitignore b/.gitignore
index 4be6e16..4e904c1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
-dist/*
\ No newline at end of file
+dist/*
+.cache/*
+.hypothesis/*
\ No newline at end of file
diff --git a/stl/hypothesis.py b/stl/hypothesis.py
new file mode 100644
index 0000000..86c0cb0
--- /dev/null
+++ b/stl/hypothesis.py
@@ -0,0 +1,30 @@
+from hypothesis_cfg import ContextFreeGrammarStrategy
+
+from hypothesis.searchstrategy.strategies import SearchStrategy
+from hypothesis.strategies import integers
+
+import stl
+
+
+GRAMMAR = {
+    'phi': (('Unary', '(', 'phi', ')'),
+            ('(', 'phi', ')',  'Binary', '(', 'phi', ')'),
+            ('AP',)),
+    'Unary': (('~',), ('G',), ('F',), ('X',)),
+    'Binary': ((' | ',), (' & ',), (' U ',)),
+}
+
+
+class SignalTemporalLogicStategy(SearchStrategy):
+    def __init__(self, max_length: int):
+        super(SearchStrategy, self).__init__()
+        self.cfg_gen = ContextFreeGrammarStrategy(
+            GRAMMAR, max_length=max_length, start='phi')
+
+    def do_draw(self, data):
+        # TODO: randomly assign all intervals
+        # TODO: randomly decide between linear predicate or boolean predicates
+        # TODO: randomly generate boolean predicate
+        # TODO: randomly generate linear predicate
+        phi =  stl.parse("".join(self.cfg_gen.do_draw(data)))
+        return phi
diff --git a/stl/test_parser.py b/stl/test_parser.py
index 92de3b8..dac702f 100644
--- a/stl/test_parser.py
+++ b/stl/test_parser.py
@@ -1,21 +1,13 @@
 # -*- coding: utf-8 -*-
 import stl
-from hypothesis import given, note
-from hypothesis_cfg import ContextFreeGrammarStrategy
+from hypothesis import given, event
 
-GRAMMAR = {
-    'phi': (('Unary', '(', 'phi', ')'),
-            ('(', 'phi', ')',  'Binary', '(', 'phi', ')'),
-            ('AP',)),
-    'Unary': (('~',), ('G',), ('F',), ('X',)),
-    'Binary': ((' | ',), (' & ',), (' U ',)),
-}
+from stl.hypothesis import SignalTemporalLogicStategy
 
 
-@given(ContextFreeGrammarStrategy(GRAMMAR, length=15, start='phi'))
-def test_invertable_repr(foo):
-    note(''.join(foo))
-    phi = stl.parse(''.join(foo))
+@given(SignalTemporalLogicStategy(max_length=25))
+def test_invertable_repr(phi):
+    event(str(phi))
     assert str(phi) == str(stl.parse(str(phi)))