diff --git a/test/mocks/knitting_machine.cpp b/test/mocks/knitting_machine.cpp
index 66334ecc..04131356 100644
--- a/test/mocks/knitting_machine.cpp
+++ b/test/mocks/knitting_machine.cpp
@@ -114,6 +114,8 @@ void KnittingMachine::moveCarriageRight() {
     moveBeltRight();
   }
   ++m_carriagePosition;
+
+  updateNeedles();
 }
 
 void KnittingMachine::moveCarriageLeft() {
@@ -121,6 +123,8 @@ void KnittingMachine::moveCarriageLeft() {
     moveBeltLeft();
   }
   --m_carriagePosition;
+
+  updateNeedles();
 }
 
 int KnittingMachine::beltPeriod() const {
@@ -138,4 +142,40 @@ bool KnittingMachine::moveCarriageCenterTowardsNeedle(int position) {
     moveCarriageLeft();
   }
   return true;
+}
+
+void KnittingMachine::setNeedleCount(int count) {
+  m_needles.clear();
+  for (int n = 0; n < count; n++) {
+    m_needles.push_back(Needle{.index = n, .position = NeedlePosition::A});
+  }
+}
+
+void KnittingMachine::setNeedlePosition(int needle, NeedlePosition position) {
+  m_needles[needle].position = position;
+}
+
+KnittingMachine::NeedlePosition KnittingMachine::getNeedlePosition(int needle) {
+  return m_needles[needle].position;
+}
+
+void KnittingMachine::setSolenoid(int solenoid, bool state) {
+  (void)state;
+  (void)solenoid;
+}
+
+void KnittingMachine::updateNeedles() {
+  for (auto& needle : m_needles) {
+    needle.update();
+  }
+}
+
+void KnittingMachine::Needle::update() {
+  switch (position) {
+  case B:
+    position = D;
+    break;
+  default:
+    break;
+  }
 }
\ No newline at end of file
diff --git a/test/mocks/knitting_machine.h b/test/mocks/knitting_machine.h
index f65db41b..0f5f0b5f 100644
--- a/test/mocks/knitting_machine.h
+++ b/test/mocks/knitting_machine.h
@@ -135,6 +135,45 @@ class KnittingMachine {
    */
   bool moveCarriageCenterTowardsNeedle(int position);
 
+  /**
+   * Initialize the needle bed with the given needle count
+   *
+   * \param count Count of (programmable) needles
+   */
+  void setNeedleCount(int count);
+
+  /**
+   * Needle positions
+   *
+   * Position "C" is not indicated on the machine nor referenced
+   * in the manual but is useful to represent an intermediate
+   * position of the needle during the selection process.
+   */
+  enum NeedlePosition { A = 0, B, C, D, E };
+
+  /**
+   * Set a needle's position
+   *
+   * \param needle the needle index (e.g. 0 to 199 on a KH-9xx)
+   * \param position the needle position (A, B…)
+   */
+  void setNeedlePosition(int needle, NeedlePosition position);
+
+  /**
+   * Get a needle's position
+   *
+   * \param needle the needle index (e.g. 0 to 199 on a KH-9xx)
+   * \returns the needle's position (A, B…)
+   */
+  NeedlePosition getNeedlePosition(int needle);
+
+  /**
+   * Set a solenoid's state
+   *
+   * \param state the solenoid's power state (true = powered)
+   */
+  void setSolenoid(int solenoid, bool state);
+
 private:
   static constexpr int STEPS_PER_NEEDLE = 4;
   static constexpr float POSITION_SENSOR_LOW_VOLTAGE = 0.2f;
@@ -251,6 +290,33 @@ class KnittingMachine {
    * center and their polarity. \see addCarriageMagnet()
    */
   std::vector<std::pair<float, bool>> m_carriageMagnets;
+
+  /**
+   * A single needle
+   */
+  struct Needle {
+    /**
+     * Needle index (0 to needle count - 1)
+     */
+    int index;
+    /**
+     * Current needle position (A, B…)
+     */
+    NeedlePosition position;
+
+    void update();
+  };
+
+  /**
+   * Needles on the bed
+   */
+  std::vector<Needle> m_needles;
+
+  /**
+   * Update the state of all the needles.
+   * Called after every carriage movement.
+   */
+  void updateNeedles();
 };
 
 #endif // KNITTINGMACHINE_H_
\ No newline at end of file
diff --git a/test/test_knitting_machine.cpp b/test/test_knitting_machine.cpp
index a4979f25..384c08fa 100644
--- a/test/test_knitting_machine.cpp
+++ b/test/test_knitting_machine.cpp
@@ -262,4 +262,29 @@ TEST(KnittingMachine, KCarriageScanBed) {
 
   km.addCarriageMagnet(0, true);
   doBedScan(km);
+}
+
+TEST(KnittingMachine, NeedleSelection) {
+  KnittingMachine km;
+
+  const int testNeedle = 47;
+  const int testSolenoid = 0;
+
+  km.setNeedleCount(200);
+  EXPECT_EQ(km.getNeedlePosition(testNeedle), KnittingMachine::A);
+
+  km.setNeedlePosition(testNeedle, KnittingMachine::B);
+  EXPECT_EQ(km.getNeedlePosition(testNeedle), KnittingMachine::B);
+  km.setSolenoid(testSolenoid, true);
+  km.putCarriageCenterInFrontOfNeedle(0);
+  while (km.moveCarriageCenterTowardsNeedle(100)) {
+  }
+
+  for (int n = 0; n < 100; n++) {
+    if (n == testNeedle) {
+      EXPECT_EQ(km.getNeedlePosition(n), KnittingMachine::D);
+    } else {
+      EXPECT_EQ(km.getNeedlePosition(n), KnittingMachine::A);
+    }
+  }
 }
\ No newline at end of file