diff --git a/b_asic/port.py b/b_asic/port.py
index d7a0cc17fcf6c998dc15ad270977702e7a7162cd..64c56bc9aef2ca71c78d08ccf0b8c20c1c68fd61 100644
--- a/b_asic/port.py
+++ b/b_asic/port.py
@@ -49,20 +49,23 @@ class Port(ABC):
     @abstractmethod
     def connect(self, port: "Port") -> Signal:
         """Create and return a signal that is connected to this port and the entered
-        port and connect this port to the signal and the entered port to the signal."""
+        port and connect this port to the signal and the entered port to the signal.
+        """
         raise NotImplementedError
 
     @abstractmethod
     def add_signal(self, signal: Signal) -> None:
         """Connect this port to the entered signal. If the entered signal isn't connected to
-        this port then connect the entered signal to the port aswell."""
+        this port then connect the entered signal to the port aswell.
+        """
         raise NotImplementedError
 
     @abstractmethod
     def disconnect(self, port: "Port") -> None:
         """Disconnect the entered port from the port by removing it from the ports signal.
         If the entered port is still connected to this ports signal then disconnect the entered
-        port from the signal aswell."""
+        port from the signal aswell.
+        """
         raise NotImplementedError
 
     @abstractmethod
@@ -112,7 +115,6 @@ class InputPort(AbstractPort):
     _source_signal: Optional[Signal]
     _value_length: Optional[int]
 
-
     def __init__(self, port_id: PortIndex, operation: Operation):
         super().__init__(port_id, operation)
         self._source_signal = None
@@ -130,11 +132,11 @@ class InputPort(AbstractPort):
     def connected_ports(self) -> List[Port]:
         return [] if self._source_signal is None or self._source_signal.source is None \
             else [self._source_signal.source]
-  
+
     @value_length.setter
     def value_length(self, bits: Optional[int]) -> None:
-        assert isinstance(bits, int) or bits is None, "Value length on input port has to be of type Int or NoneType."
-        assert bits is None or bits >= 0, "Value length on input port has to be a non-negative integer or None."
+        assert (isinstance(bits, int) and bits >= 0) or bits is None, \
+            "Value length on input port has to be a non-negative integer or None."
         self._value_length = bits
 
     def signal_count(self) -> int:
@@ -142,7 +144,7 @@ class InputPort(AbstractPort):
 
     def connect(self, port: "OutputPort") -> Signal:
         assert self._source_signal is None, "Connecting new port to already connected input port."
-        return Signal(port, self)        # self._source_signal is set by the signal constructor
+        return Signal(port, self)        # self._source_signal is set by the signal constructor.
 
     def add_signal(self, signal: Signal) -> None:
         assert self._source_signal is None, "Connecting new port to already connected input port."
@@ -159,12 +161,13 @@ class InputPort(AbstractPort):
         old_signal: Signal = self._source_signal
         self._source_signal = None
         if self is old_signal.destination:
-            # Disconnect the dest of the signal if this inputport currently is the dest
+            # Disconnect the dest of the signal if this inputport currently is the dest.
             old_signal.remove_destination()
 
     def clear(self) -> None:
         self.remove_signal(self._source_signal)
 
+
 class OutputPort(AbstractPort):
     """Output port.
     TODO: More info.
@@ -193,14 +196,14 @@ class OutputPort(AbstractPort):
         return len(self._destination_signals)
 
     def connect(self, port: InputPort) -> Signal:
-        return Signal(self, port)      # Signal is added to self._destination_signals in signal constructor
+        return Signal(self, port)  # Signal is added to self._destination_signals in signal constructor.
 
     def add_signal(self, signal: Signal) -> None:
         assert signal not in self.signals, \
                 "Attempting to connect to Signal already connected."
         self._destination_signals.append(signal)
         if self is not signal.source:
-            # Connect this outputport to the signal if it isn't already
+            # Connect this outputport to the signal if it isn't already.
             signal.set_source(self)
 
     def disconnect(self, port: InputPort) -> None:
diff --git a/test/test_inputport.py b/test/test_inputport.py
index 910b2700e25f4cb8d4148cc8bfb6b89126576a7b..a0f24e4e90cb69553a200e0a8402ac248c14d3b9 100644
--- a/test/test_inputport.py
+++ b/test/test_inputport.py
@@ -24,18 +24,16 @@ def dangling_sig():
     return Signal()
 
 @pytest.fixture
-def s_w_source():
-    out_port = OutputPort(0, None)
+def s_w_source(out_port):
     return Signal(source=out_port)
 
 @pytest.fixture
-def sig_with_dest():
-    #inp_port = InputPort(0, None)
-    return Signal(destination=inp_port())
+def sig_with_dest(inp_port):
+    return Signal(destination=inp_port)
 
 @pytest.fixture
-def connected_sig():
-    return Signal(source=out_port(), destination=inp_port())
+def connected_sig(inp_port, out_port):
+    return Signal(source=out_port, destination=inp_port)
 
 def test_connect_then_disconnect(inp_port, out_port):
     """Test connect unused port to port."""
@@ -104,4 +102,4 @@ def test_set_value_length_float(inp_port):
 def test_set_value_length_pos_then_none(inp_port):
     inp_port.value_length = 10
     inp_port.value_length = None
-    assert inp_port.value_length == None
\ No newline at end of file
+    assert inp_port.value_length is None