diff --git a/main.go b/main.go
index fe4e6df..b14d04c 100644
--- a/main.go
+++ b/main.go
@@ -82,6 +82,10 @@ func initialModel(fullscreen bool, colorLeft string, colorRight string) model {
 	inputs[2].Placeholder = "Number of intervals"
 	inputs[2].Validate = validateInt
 
+	if colorLeft == "" || colorRight == "" {
+		panic("Color values must be provided")
+	}
+
 	return model{
 		inputs:        inputs,
 		progressBar:   progress.New(progress.WithScaledGradient(colorLeft, colorRight)),
@@ -113,18 +117,24 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.KeyMsg:
 		switch msg.String() {
-		case "ctrl+c":
+		case "ctrl+c", "esc":
 			// Gracefully exit
 			return m, tea.Quit
 
-		case "tab":
+		case "q":
+			// Quit the program if on the timer screen
+			if m.currentScreen == timerScreen {
+				return m, tea.Quit
+			}
+
+		case "tab", "ctrl+n", "j", "down":
 			// Move to the next input field
 			m.focusIndex = (m.focusIndex + 1) % len(m.inputs)
 			m.updateFocus()
 
 			return m, nil
 
-		case "shift+tab":
+		case "shift+tab", "ctrl+p", "k", "up":
 			// Move to the previous input field
 			m.focusIndex = (m.focusIndex - 1 + len(m.inputs)) % len(m.inputs)
 			m.updateFocus()
@@ -175,6 +185,7 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 
 	case timeMsg:
 		// Handle timer update for each second
+		// TODO: Use absolute times to tick down remaining time rather than incrementing seconds
 		m.remaining -= time.Second
 		if m.remaining < 0 {
 			if m.isFocus {
@@ -389,6 +400,9 @@ func main() {
 				return nil
 			}
 
+			fmt.Printf("color-left: %s\n", c.String("color-left"))
+			fmt.Printf("color-right: %s\n", c.String("color-right"))
+
 			m := initialModel(c.Bool("fullscreen"), c.String("color-left"), c.String("color-right"))
 
 			// Collect command flags
diff --git a/main_test.go b/main_test.go
new file mode 100644
index 0000000..ebaea3d
--- /dev/null
+++ b/main_test.go
@@ -0,0 +1,156 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	tea "github.com/charmbracelet/bubbletea"
+)
+
+// assertEqual checks if two values are equal and reports an error if they are not.
+func assertEqual(t *testing.T, actual, expected interface{}, msg string) {
+	t.Helper()
+
+	if actual != expected {
+		t.Errorf("%s: expected %v, got %v", msg, expected, actual)
+	}
+}
+
+// assertNotEqual checks if two values are not equal and reports an error if they are.
+func assertNotEqual(t *testing.T, actual, expected interface{}, msg string) {
+	t.Helper()
+
+	if actual == expected {
+		t.Errorf("%s: expected %v to be different from %v", msg, actual, expected)
+	}
+}
+
+// TestParseDuration tests the parseDuration function
+func TestParseDuration(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected time.Duration
+		hasError bool
+	}{
+		{"10", 10 * time.Minute, false},
+		{"1h", 1 * time.Hour, false},
+		{"invalid", 0, true},
+	}
+
+	for _, test := range tests {
+		result, err := parseDuration(test.input)
+		if test.hasError {
+			assertNotEqual(t, err, nil, "Expected an error for input "+test.input)
+		} else {
+			assertEqual(t, err, nil, "Did not expect an error for input "+test.input)
+			assertEqual(t, result, test.expected, "Expected duration for input "+test.input)
+		}
+	}
+}
+
+// TestRunCommands tests the runCommands function
+func TestRunCommands(t *testing.T) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Redirect stdout and stderr to the pipe
+	oldStdout := os.Stdout
+	oldStderr := os.Stderr
+	os.Stdout = w
+	os.Stderr = w
+
+	t.Cleanup(func() {
+		os.Stdout = oldStdout
+		os.Stderr = oldStderr
+
+		w.Close()
+	})
+
+	m := model{}
+	m.runCommands([]string{"echo Hello, World!"})
+
+	w.Close()
+
+	var buf bytes.Buffer
+
+	if _, err = io.Copy(&buf, r); err != nil {
+		t.Fatal(err)
+	}
+
+	output := buf.String()
+	assertEqual(t, strings.Contains(output, "Hello, World!"), true, "Expected output to contain 'Hello, World!'")
+}
+
+// TestInputView tests the Update method of the model for the input view
+func TestInputView(t *testing.T) {
+	m := initialModel(false, "#ffdd57", "#57ddff")
+	m.View()
+
+	assertEqual(t, m.currentScreen, inputScreen, "Expected currentScreen to be inputScreen")
+	assertEqual(t, m.focusIndex, 0, "Expected focusIndex to be 0")
+
+	m.inputs[m.focusIndex].SetValue("10")
+
+	var msg tea.Msg
+
+	// Test tab key press
+	msg = tea.KeyMsg{Type: tea.KeyTab}
+	updatedModel, _ := m.Update(msg)
+	m = updatedModel.(model)
+	assertEqual(t, m.focusIndex, 1, "Expected focusIndex to be 1")
+
+	// Test shift+tab key press
+	msg = tea.KeyMsg{Type: tea.KeyShiftTab}
+	updatedModel, _ = m.Update(msg)
+	m = updatedModel.(model)
+	assertEqual(t, m.focusIndex, 0, "Expected focusIndex to be 0")
+
+	// Enter last value and test enter key press
+	for i := m.focusIndex; i < 2; i++ {
+		msg = tea.KeyMsg{Type: tea.KeyTab}
+		updatedModel, _ = m.Update(msg)
+		m = updatedModel.(model)
+		m.inputs[m.focusIndex].SetValue("10")
+	}
+
+	msg = tea.KeyMsg{Type: tea.KeyEnter}
+	updatedModel, resultCmd := m.Update(msg)
+	m = updatedModel.(model)
+
+	assertEqual(t, m.err, nil, "Expected no error")
+	assertNotEqual(t, resultCmd, nil, "Expected resultCmd to be not nil")
+	assertEqual(t, m.currentScreen, timerScreen, "Expected currentScreen to be timerScreen")
+	assertEqual(t, m.remaining, 10*time.Minute, "Expected remaining to be 10 minutes")
+
+	// Test timer view
+	m.View()
+
+	oneSec := timeMsg(time.Now().Add(1 * time.Second))
+	updatedModel, _ = m.Update(oneSec)
+	m = updatedModel.(model)
+
+	assertEqual(t, m.state, "Focus", "Expected state to be 'Focus'")
+	assertEqual(t, m.remaining, 9*time.Minute+59*time.Second, "Expected remaining to be 9 minutes 59 seconds")
+
+	// Test switch to break time
+	m.remaining = 0
+	updatedModel, _ = m.Update(oneSec)
+	m = updatedModel.(model)
+
+	assertEqual(t, m.state, "Break", "Expected state to be 'Break'")
+	assertEqual(t, m.remaining, 9*time.Minute+59*time.Second, "Expected remaining to be 9 minutes 59 seconds")
+
+	// Switch back to focus time
+	m.remaining = 0
+	updatedModel, _ = m.Update(oneSec)
+	m = updatedModel.(model)
+
+	assertEqual(t, m.state, "Focus", "Expected state to be 'Focus'")
+	assertEqual(t, m.remaining, 9*time.Minute+59*time.Second, "Expected remaining to be 9 minutes 59 seconds")
+}