3 files changed, 47 insertions, 7 deletions

diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..542050b
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,7 @@
+[report]
+exclude_lines =
+    pragma: no cover
+    raise AssertionError
+    raise NotImplementedError
+    if 0:
+    if __name__ == .__main__.:
\ No newline at end of file
diff --git a/pyecsca/ec/context.py b/pyecsca/ec/context.py
index 0c21942..48dcc1d 100644
--- a/pyecsca/ec/context.py
+++ b/pyecsca/ec/context.py
@@ -72,6 +72,9 @@ class Action(object):
             self.roots[k] = self.intermediates[k]
         self.output_points.append(point)
 
+    def __repr__(self):
+        return f"Action({self.formula}, {self.input_points}) = {self.output_points}"
+
 
 @public
 class Context(object):
@@ -86,11 +89,11 @@ class Context(object):
 
     def _execute(self, formula: Formula, *points: Point, **params: Mod) -> Tuple[Point, ...]:
         if len(points) != formula.num_inputs:
-            raise ValueError
+            raise ValueError(f"Wrong number of inputs for {formula}.")
         coords = {}
         for i, point in enumerate(points):
             if point.coordinate_model != formula.coordinate_model:
-                raise ValueError
+                raise ValueError(f"Wrong coordinate model of point {point}.")
             for coord, value in point.coords.items():
                 coords[coord + str(i + 1)] = value
         locals = {**coords, **params}
@@ -106,8 +109,6 @@ class Context(object):
             full_resulting = {}
             for variable in formula.coordinate_model.variables:
                 full_variable = variable + ind
-                if full_variable not in locals:
-                    continue
                 resulting[variable] = locals[full_variable]
                 full_resulting[full_variable] = locals[full_variable]
             point = Point(formula.coordinate_model, **resulting)
diff --git a/test/ec/test_context.py b/test/ec/test_context.py
index 51fefd7..9e56afb 100644
--- a/test/ec/test_context.py
+++ b/test/ec/test_context.py
@@ -1,8 +1,21 @@
+import ast
 from unittest import TestCase
 
-from pyecsca.ec.context import local, DefaultContext
+from pyecsca.ec.context import local, DefaultContext, OpResult, NullContext, getcontext
+from pyecsca.ec.coordinates import AffineCoordinateModel
+from pyecsca.ec.mod import Mod
 from pyecsca.ec.mult import LTRMultiplier
-from test.ec.curves import get_secp128r1
+from pyecsca.ec.point import Point
+from .curves import get_secp128r1
+
+
+class OpResultTests(TestCase):
+
+    def test_repr(self):
+        for op, char in zip((ast.Add(), ast.Sub(), ast.Mult(), ast.Div()), "+-*/"):
+            res = OpResult("X1", Mod(0, 5), op, Mod(2, 5), Mod(3, 5))
+            self.assertEqual(str(res), "X1")
+            self.assertEqual(repr(res), "X1 = 2{}3".format(char))
 
 
 class ContextTests(TestCase):
@@ -15,9 +28,28 @@ class ContextTests(TestCase):
                                   self.coords.formulas["dbl-1998-cmo"], self.coords.formulas["z"])
 
     def test_null(self):
-        self.mult.multiply(59, self.base)
+        with local() as ctx:
+            self.mult.multiply(59, self.base)
+        self.assertIsInstance(ctx, NullContext)
 
     def test_default(self):
         with local(DefaultContext()) as ctx:
             self.mult.multiply(59, self.base)
         self.assertEqual(len(ctx.actions), 10)
+
+    def test_execute(self):
+        with self.assertRaises(ValueError):
+            getcontext().execute(self.coords.formulas["z"], self.base, self.base)
+        with self.assertRaises(ValueError):
+            getcontext().execute(self.coords.formulas["z"],
+                                 Point(AffineCoordinateModel(self.secp128r1.curve.model),
+                                       x=Mod(1, 5), y=Mod(2, 5)))
+
+    def test_repr(self):
+        with local(DefaultContext()) as default:
+            self.mult.multiply(59, self.base)
+        str(default)
+        str(default.actions)
+        with local(NullContext()) as null:
+            self.mult.multiply(59, self.base)
+        str(null)