diff --git a/docs/CHANGES.rst b/docs/CHANGES.rst
index e489829..7e48fff 100644
--- a/docs/CHANGES.rst
+++ b/docs/CHANGES.rst
@@ -25,6 +25,9 @@ Changes
 
 - Imports like `from _a import b` or `from a._b import x` are now forbidden.
 
+- Bring test coverage to 100 %.
+
+
 
 4.0b3 (2018-04-12)
 ------------------
diff --git a/setup.cfg b/setup.cfg
index 2bd4c9b..409438b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -53,6 +53,8 @@ omit =
 
 [coverage:report]
 precision = 2
+show_missing = True
+sort = Name
 
 [coverage:html]
 directory = _build/coverage
diff --git a/src/RestrictedPython/transformer.py b/src/RestrictedPython/transformer.py
index 6b882c7..b67238c 100644
--- a/src/RestrictedPython/transformer.py
+++ b/src/RestrictedPython/transformer.py
@@ -313,8 +313,11 @@ def gen_unpack_wrapper(self, node, target, ctx='store'):
             ctx = ast.Store()
         elif ctx == 'param':
             ctx = ast.Param()
-        else:
-            raise Exception('Unsupported context type.')
+        else:  # pragma: no cover
+            # Only store and param are defined ctx.
+            raise NotImplementedError(
+                'Unsupported context type: "{name}".'.format(name=type(ctx)),
+            )
 
         # This node is used to catch the tuple in a tmp variable.
         tmp_target = ast.Name(tmp_name, ctx)
@@ -380,8 +383,9 @@ def transform_slice(self, slice_):
                 dims.elts.append(self.transform_slice(item))
             return dims
 
-        else:
-            raise Exception("Unknown slice type: {0}".format(slice_))
+        else:  # pragma: no cover
+            # Index, Slice and ExtSlice are only defined Slice types.
+            raise NotImplementedError("Unknown slice type: {0}".format(slice_))
 
     def check_name(self, node, name, allow_magic_methods=False):
         """Check names if they are allowed.
@@ -897,8 +901,10 @@ def visit_Attribute(self, node):
             node.value = new_value
             return node
 
-        else:
-            return self.node_contents_visit(node)
+        else:  # pragma: no cover
+            # Impossible Case only ctx Load, Store and Del are defined in ast.
+            raise NotImplementedError(
+                "Unknown ctx type: {0}".format(type(node.ctx)))
 
     # Subscripting
 
@@ -942,8 +948,10 @@ def visit_Subscript(self, node):
             node.value = new_value
             return node
 
-        else:
-            return node
+        else:  # pragma: no cover
+            # Impossible Case only ctx Load, Store and Del are defined in ast.
+            raise NotImplementedError(
+                "Unknown ctx type: {0}".format(type(node.ctx)))
 
     def visit_Index(self, node):
         """
@@ -1088,8 +1096,14 @@ def visit_AugAssign(self, node):
 
             copy_locations(new_node, node)
             return new_node
-
-        return node
+        else:  # pragma: no cover
+            # Impossible Case - Only Node Types:
+            # * Name
+            # * Attribute
+            # * Subscript
+            # defined, those are checked before.
+            raise NotImplementedError(
+                "Unknown target type: {0}".format(type(node.target)))
 
     def visit_Print(self, node):
         """Checks and mutates a print statement.
@@ -1297,6 +1311,7 @@ def visit_Lambda(self, node):
         node = self.node_contents_visit(node)
 
         if IS_PY3:
+            # Implicit Tuple unpacking is not anymore avaliable in Python3
             return node
 
         # Check for tuple parameters which need _getiter_ protection
@@ -1397,7 +1412,7 @@ def visit_Module(self, node):
 
         # Inject the print collector after 'from __future__ import ....'
         position = 0
-        for position, child in enumerate(node.body):
+        for position, child in enumerate(node.body):  # pragma: no branch
             if not isinstance(child, ast.ImportFrom):
                 break
 
diff --git a/tests/test_Guards.py b/tests/test_Guards.py
index 0155668..8f1014a 100644
--- a/tests/test_Guards.py
+++ b/tests/test_Guards.py
@@ -1,6 +1,7 @@
 from RestrictedPython._compat import IS_PY2
 from RestrictedPython.Guards import guarded_unpack_sequence
 from RestrictedPython.Guards import safe_builtins
+from RestrictedPython.Guards import safer_getattr
 from tests import e_eval
 from tests import e_exec
 
@@ -187,3 +188,29 @@ def test_Guards__safer_getattr__2(e_exec):
         assert 'Using format() on a unicode is not safe.' == str(err.value)
     else:
         assert 'Using format() on a str is not safe.' == str(err.value)
+
+
+SAFER_GETATTR_ALLOWED = """\
+class A:
+
+    def __init__(self, value):
+        self.value = value
+
+a = A(2)
+result = getattr(a, 'value')
+"""
+
+
+@pytest.mark.parametrize(*e_exec)
+def test_Guards__safer_getattr__3(e_exec):
+    """It allows to use `safer_getattr`."""
+    restricted_globals = dict(
+        __builtins__=safe_builtins,
+        __name__=None,
+        __metaclass__=type,
+        _write_=lambda x: x,
+        getattr=safer_getattr,
+        result=None,
+    )
+    e_exec(SAFER_GETATTR_ALLOWED, restricted_globals)
+    assert restricted_globals['result'] == 2
diff --git a/tests/transformer/test_lambda.py b/tests/transformer/test_lambda.py
index c882ad4..4218226 100644
--- a/tests/transformer/test_lambda.py
+++ b/tests/transformer/test_lambda.py
@@ -1,5 +1,6 @@
 from RestrictedPython._compat import IS_PY2
 from RestrictedPython._compat import IS_PY3
+from RestrictedPython.Eval import default_guarded_getiter
 from RestrictedPython.Guards import guarded_unpack_sequence
 from tests import c_exec
 from tests import e_exec
@@ -117,3 +118,58 @@ def test_RestrictingNodeTransformer__visit_Lambda__9(
     assert 2 == _getiter_.call_count
     _getiter_.assert_any_call((1, (2, 3)))
     _getiter_.assert_any_call((2, 3))
+
+
+LAMBDA_FUNC_1 = """
+g = lambda x: x ** 2
+"""
+
+
+@pytest.mark.parametrize(*e_exec)
+def test_RestrictingNodeTransformer__visit_Lambda__10(e_exec):
+    """Simple lambda functions are allowed."""
+    restricted_globals = dict(
+        g=None,
+    )
+    e_exec(LAMBDA_FUNC_1, restricted_globals)
+    assert 4 == restricted_globals['g'](2)
+
+
+LAMBDA_FUNC_2 = """
+g = lambda (x, y) : (x ** 2, x + y)
+"""
+
+
+@pytest.mark.skipif(
+    IS_PY3,
+    reason="tuple parameter unpacking is gone in python 3")
+@pytest.mark.parametrize(*e_exec)
+def test_RestrictingNodeTransformer__visit_Lambda__11(e_exec):
+    """Lambda functions with tuple unpacking are allowed."""
+    restricted_globals = dict(
+        g=None,
+        _unpack_sequence_=guarded_unpack_sequence,
+        _getiter_=default_guarded_getiter,
+    )
+    e_exec(LAMBDA_FUNC_2, restricted_globals)
+    assert (9, 5) == restricted_globals['g']((3, 2))
+
+
+LAMBDA_FUNC_3 = """
+g = lambda (x, y), z : (x ** y, x + z)
+"""
+
+
+@pytest.mark.skipif(
+    IS_PY3,
+    reason="tuple parameter unpacking is gone in python 3")
+@pytest.mark.parametrize(*e_exec)
+def test_RestrictingNodeTransformer__visit_Lambda__12(e_exec):
+    """Lambda functions with tuple unpacking and simple params are allowed."""
+    restricted_globals = dict(
+        g=None,
+        _unpack_sequence_=guarded_unpack_sequence,
+        _getiter_=default_guarded_getiter,
+    )
+    e_exec(LAMBDA_FUNC_3, restricted_globals)
+    assert (64, 6) == restricted_globals['g']((4, 3), 2)
diff --git a/tox.ini b/tox.ini
index ab98662..8e6bfae 100644
--- a/tox.ini
+++ b/tox.ini
@@ -64,7 +64,7 @@ commands =
     coverage combine
     coverage html
     coverage xml
-    coverage report
+    coverage report --fail-under=100.0
 
 [testenv:isort-apply]
 basepython = python2.7