diff --git a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalCustomTimer.kt b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalCustomTimer.kt
index 7cae544..1cd9a69 100644
--- a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalCustomTimer.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalCustomTimer.kt
@@ -1,16 +1,16 @@
 package be.ugent.sel.studeez.data.local.models.timer_functional
 
-class FunctionalCustomTimer(studyTime: Int): FunctionalTimer(studyTime) {
+class FunctionalCustomTimer(studyTime: Int) : FunctionalTimer(studyTime) {
 
     override fun tick() {
-        if (time.getTime() == 0) {
-            view = "Done!"
+        if (time.time == 0) {
+            view = DONE
         } else {
             time.minOne()
         }
     }
 
     override fun hasEnded(): Boolean {
-        return time.getTime() == 0
+        return time.time == 0
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalEndlessTimer.kt b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalEndlessTimer.kt
index 45eecda..1c055b5 100644
--- a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalEndlessTimer.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalEndlessTimer.kt
@@ -1,6 +1,6 @@
 package be.ugent.sel.studeez.data.local.models.timer_functional
 
-class FunctionalEndlessTimer() : FunctionalTimer(0){
+class FunctionalEndlessTimer() : FunctionalTimer(0) {
 
     override fun hasEnded(): Boolean {
         return false
diff --git a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalPomodoroTimer.kt b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalPomodoroTimer.kt
index ef0bf03..326869a 100644
--- a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalPomodoroTimer.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalPomodoroTimer.kt
@@ -3,25 +3,25 @@ package be.ugent.sel.studeez.data.local.models.timer_functional
 class FunctionalPomodoroTimer(
     private var studyTime: Int,
     private var breakTime: Int, repeats: Int
-): FunctionalTimer(studyTime) {
+) : FunctionalTimer(studyTime) {
 
-    private var breaksRemaining = repeats
-    private var isInBreak = false
+    var breaksRemaining = repeats
+    var isInBreak = false
 
     override fun tick() {
-        if (time.getTime() == 0 && breaksRemaining == 0){
-            view = "Done!"
+        if (time.time == 0 && breaksRemaining == 0) {
+            view = DONE
             return
         }
 
-        if (time.getTime() == 0) {
+        if (time.time == 0) {
             if (isInBreak) {
                 breaksRemaining--
-                view = "Focus! ($breaksRemaining breaks remaining)"
-                time.setTime(studyTime)
+                view = FOCUS_REMAINING(breaksRemaining)
+                time.time = studyTime
             } else {
-                view = "Take a break!"
-                time.setTime(breakTime)
+                view = BREAK
+                time.time = breakTime
             }
             isInBreak = !isInBreak
         }
@@ -29,6 +29,6 @@ class FunctionalPomodoroTimer(
     }
 
     override fun hasEnded(): Boolean {
-        return breaksRemaining == 0 && time.getTime() == 0
+        return breaksRemaining == 0 && time.time == 0
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalTimer.kt b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalTimer.kt
index e6965ab..8faf6d0 100644
--- a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalTimer.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalTimer.kt
@@ -1,19 +1,22 @@
 package be.ugent.sel.studeez.data.local.models.timer_functional
 
 abstract class FunctionalTimer(initialValue: Int) {
-    protected val time: Time = Time(initialValue)
-    protected var view: String = "Focus"
+    val time: Time = Time(initialValue)
+    var view: String = FOCUS
 
     fun getHoursMinutesSeconds(): HoursMinutesSeconds {
         return time.getAsHMS()
     }
 
-    fun getViewString(): String {
-        return view
-    }
-
     abstract fun tick()
 
     abstract fun hasEnded(): Boolean
 
+    companion object {
+        const val FOCUS: String = "Focus"
+        const val DONE: String = "Done!"
+        const val BREAK: String = "Take a break!"
+        val FOCUS_REMAINING: (Int) -> String = { n -> "Focus! ($n breaks remaining)" }
+    }
+
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/Time.kt b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/Time.kt
index ff89516..ec7702d 100644
--- a/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/Time.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/Time.kt
@@ -2,7 +2,7 @@ package be.ugent.sel.studeez.data.local.models.timer_functional
 
 class Time(initialTime: Int) {
 
-    private var time = initialTime
+    var time = initialTime
 
     fun minOne() {
         time--
@@ -12,14 +12,6 @@ class Time(initialTime: Int) {
         time++
     }
 
-    fun setTime(newTime: Int) {
-        time = newTime
-    }
-
-    fun getTime(): Int {
-        return time
-    }
-
     fun getAsHMS(): HoursMinutesSeconds {
         val hours: Int = time / (60 * 60)
         val minutes: Int = (time / (60)) % 60
diff --git a/app/src/main/java/be/ugent/sel/studeez/screens/session/SessionScreen.kt b/app/src/main/java/be/ugent/sel/studeez/screens/session/SessionScreen.kt
index d69470e..05a7d3d 100644
--- a/app/src/main/java/be/ugent/sel/studeez/screens/session/SessionScreen.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/screens/session/SessionScreen.kt
@@ -50,7 +50,7 @@ private fun Timer(viewModel: SessionViewModel = hiltViewModel()) {
             fontSize = 80.sp
         )
         Text(
-            text = viewModel.getTimer().getViewString(),
+            text = viewModel.getTimer().view,
             modifier = Modifier.fillMaxWidth(),
             textAlign = TextAlign.Center,
             fontWeight = FontWeight.Light,
diff --git a/app/src/test/java/be/ugent/sel/studeez/ExampleUnitTest.kt b/app/src/test/java/be/ugent/sel/studeez/ExampleUnitTest.kt
deleted file mode 100644
index 4ff9e1c..0000000
--- a/app/src/test/java/be/ugent/sel/studeez/ExampleUnitTest.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-package be.ugent.sel.studeez
-
-import org.junit.Test
-
-import org.junit.Assert.*
-
-/**
- * Example local unit test, which will execute on the development machine (host).
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-class ExampleUnitTest {
-    @Test
-    fun addition_isCorrect() {
-        assertEquals(4, 2 + 2)
-    }
-}
\ No newline at end of file
diff --git a/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalCustomTimerUnitTest.kt b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalCustomTimerUnitTest.kt
new file mode 100644
index 0000000..90c4fcd
--- /dev/null
+++ b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalCustomTimerUnitTest.kt
@@ -0,0 +1,44 @@
+package be.ugent.sel.studeez.timer_functional
+
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalCustomTimer
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalTimer
+import org.junit.Assert
+import org.junit.Test
+
+class FunctionalCustomTimerUnitTest : FunctionalTimerUnitTest() {
+    override fun setTimer() {
+        timer = FunctionalCustomTimer(time)
+    }
+
+    @Test
+    override fun testOneTick() {
+        timer.tick()
+        Assert.assertEquals(
+            time - 1,
+            timer.time.time,
+        )
+    }
+
+    @Test
+    override fun multipleTicks() {
+        val n = 10
+        for (i in 1..n) {
+            timer.tick()
+        }
+        Assert.assertEquals(
+            time - n,
+            timer.time.time,
+        )
+    }
+
+    @Test
+    override fun testEnded() {
+        timer = FunctionalCustomTimer(0)
+        timer.tick()
+        Assert.assertTrue(timer.hasEnded())
+        Assert.assertEquals(
+            FunctionalTimer.DONE,
+            timer.view
+        )
+    }
+}
\ No newline at end of file
diff --git a/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalEndlessTimerUnitTest.kt b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalEndlessTimerUnitTest.kt
new file mode 100644
index 0000000..e0e98af
--- /dev/null
+++ b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalEndlessTimerUnitTest.kt
@@ -0,0 +1,46 @@
+package be.ugent.sel.studeez.timer_functional
+
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalEndlessTimer
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalTimer
+import org.junit.Assert
+import org.junit.Test
+
+class FunctionalEndlessTimerUnitTest : FunctionalTimerUnitTest() {
+    override fun setTimer() {
+        timer = FunctionalEndlessTimer()
+    }
+
+    @Test
+    override fun testOneTick() {
+        timer.tick()
+        Assert.assertEquals(
+            1,
+            timer.time.time
+        )
+    }
+
+    @Test
+    override fun multipleTicks() {
+        val n = 10
+        for (i in 1..n) {
+            timer.tick()
+        }
+        Assert.assertEquals(
+            n,
+            timer.time.time
+        )
+    }
+
+    @Test
+    override fun testEnded() {
+        val n = 1000
+        for (i in 1..n) {
+            timer.tick()
+            Assert.assertFalse(timer.hasEnded())
+            Assert.assertEquals(
+                FunctionalTimer.FOCUS,
+                timer.view
+            )
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalTimerUnitTest.kt b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalTimerUnitTest.kt
new file mode 100644
index 0000000..4d26d06
--- /dev/null
+++ b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FunctionalTimerUnitTest.kt
@@ -0,0 +1,33 @@
+package be.ugent.sel.studeez.timer_functional
+
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalTimer
+import org.junit.Before
+import org.junit.Test
+
+abstract class FunctionalTimerUnitTest {
+    protected lateinit var timer: FunctionalTimer
+    protected open val hours = 4
+    protected open val minutes = 20
+    protected open val seconds = 39
+    protected var time: Int = 0
+
+    @Before
+    fun setup() {
+        time = seconds + minutes * 60 + hours * 60 * 60
+        setTimer()
+    }
+
+    /**
+     * The timer-property should be set to the right implementation in this method.
+     */
+    abstract fun setTimer()
+
+    @Test
+    abstract fun testOneTick()
+
+    @Test
+    abstract fun multipleTicks()
+
+    @Test
+    abstract fun testEnded()
+}
\ No newline at end of file
diff --git a/app/src/test/java/be/ugent/sel/studeez/timer_functional/FuntionalPomodoroTimerUnitTest.kt b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FuntionalPomodoroTimerUnitTest.kt
new file mode 100644
index 0000000..d8229a5
--- /dev/null
+++ b/app/src/test/java/be/ugent/sel/studeez/timer_functional/FuntionalPomodoroTimerUnitTest.kt
@@ -0,0 +1,98 @@
+package be.ugent.sel.studeez.timer_functional
+
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalPomodoroTimer
+import be.ugent.sel.studeez.data.local.models.timer_functional.FunctionalTimer
+import org.junit.Assert
+import org.junit.Test
+
+class FuntionalPomodoroTimerUnitTest : FunctionalTimerUnitTest() {
+    private val breakTime = 10
+    private val breaks = 2
+    override val hours = 0
+    override val minutes = 0
+    override val seconds = 10
+    private lateinit var pomodoroTimer: FunctionalPomodoroTimer
+
+    override fun setTimer() {
+        pomodoroTimer = FunctionalPomodoroTimer(time, breakTime, breaks)
+    }
+
+    @Test
+    override fun testOneTick() {
+        pomodoroTimer.tick()
+        Assert.assertEquals(
+            time - 1,
+            pomodoroTimer.time.time,
+        )
+        Assert.assertFalse(pomodoroTimer.isInBreak)
+        Assert.assertEquals(
+            breaks,
+            pomodoroTimer.breaksRemaining,
+        )
+        Assert.assertEquals(
+            FunctionalTimer.FOCUS,
+            pomodoroTimer.view,
+        )
+    }
+
+    @Test
+    override fun multipleTicks() {
+        val n = 10
+        for (i in 1..n) {
+            pomodoroTimer.tick()
+        }
+        Assert.assertEquals(
+            time - n,
+            pomodoroTimer.time.time
+        )
+    }
+
+    @Test
+    override fun testEnded() {
+        pomodoroTimer = FunctionalPomodoroTimer(0, 0, 0)
+        pomodoroTimer.tick()
+        Assert.assertTrue(pomodoroTimer.hasEnded())
+        Assert.assertEquals(
+            FunctionalTimer.DONE,
+            pomodoroTimer.view,
+        )
+    }
+
+    @Test
+    fun switchToBreak() {
+        for (i in 0..10) {
+            pomodoroTimer.tick()
+        }
+        Assert.assertFalse(pomodoroTimer.hasEnded())
+        Assert.assertTrue(pomodoroTimer.isInBreak)
+        Assert.assertEquals(
+            FunctionalTimer.BREAK,
+            pomodoroTimer.view
+        )
+    }
+
+    @Test
+    fun switchToStudying() {
+        for (i in 0..time) {
+            pomodoroTimer.tick()
+        }
+        Assert.assertTrue(pomodoroTimer.isInBreak)
+        Assert.assertEquals(
+            FunctionalTimer.BREAK,
+            pomodoroTimer.view
+        )
+        for (i in 0..breakTime) {
+            pomodoroTimer.tick()
+        }
+        Assert.assertFalse(pomodoroTimer.isInBreak)
+        val breaksRemaining = breaks - 1
+        Assert.assertEquals(
+            breaksRemaining,
+            pomodoroTimer.breaksRemaining
+        )
+        Assert.assertEquals(
+            FunctionalTimer.FOCUS_REMAINING(breaksRemaining),
+            pomodoroTimer.view
+        )
+    }
+}
\ No newline at end of file
diff --git a/app/src/test/java/be/ugent/sel/studeez/timer_functional/TimeUnitTest.kt b/app/src/test/java/be/ugent/sel/studeez/timer_functional/TimeUnitTest.kt
new file mode 100644
index 0000000..86fdce8
--- /dev/null
+++ b/app/src/test/java/be/ugent/sel/studeez/timer_functional/TimeUnitTest.kt
@@ -0,0 +1,81 @@
+package be.ugent.sel.studeez.timer_functional
+
+import be.ugent.sel.studeez.data.local.models.timer_functional.HoursMinutesSeconds
+import be.ugent.sel.studeez.data.local.models.timer_functional.Time
+import org.junit.Assert
+import org.junit.Before
+import org.junit.Test
+
+class TimeUnitTest {
+    private val hours = 4
+    private val minutes = 20
+    private val seconds = 39
+    private val time: Time = Time(seconds + minutes * 60 + hours * 60 * 60)
+
+    @Before
+    fun setup() {
+
+    }
+
+    @Test
+    fun formatTime() {
+        Assert.assertEquals(
+            HoursMinutesSeconds(
+                hours.toString().padStart(2, '0'),
+                minutes.toString().padStart(2, '0'),
+                seconds.toString().padStart(2, '0'),
+            ),
+            time.getAsHMS(),
+        )
+    }
+
+    @Test
+    fun getTime() {
+        Assert.assertEquals(
+            seconds + minutes * 60 + hours * 60 * 60,
+            time.time,
+        )
+    }
+
+    @Test
+    fun minOne() {
+        time.minOne()
+        Assert.assertEquals(
+            (seconds + minutes * 60 + hours * 60 * 60) - 1,
+            time.time,
+        )
+    }
+
+    @Test
+    fun plusOne() {
+        time.plusOne()
+        Assert.assertEquals(
+            (seconds + minutes * 60 + hours * 60 * 60) + 1,
+            time.time,
+        )
+    }
+
+    @Test
+    fun minMultiple() {
+        val n = 10
+        for (i in 1 .. n) {
+            time.minOne()
+        }
+        Assert.assertEquals(
+            (seconds + minutes * 60 + hours * 60 * 60) - n,
+            time.time,
+        )
+    }
+
+    @Test
+    fun plusMultiple() {
+        val n = 10
+        for (i in 1 .. n) {
+            time.plusOne()
+        }
+        Assert.assertEquals(
+            (seconds + minutes * 60 + hours * 60 * 60) + n,
+            time.time,
+        )
+    }
+}
\ No newline at end of file