Refactor cointoss logic into separate package and add unit tests

Author: chrisreddington

.github/workflows/ci.yml

@@ -17,4 +17,7 @@ jobs:
           go-version: '1.23' # You can change this to your desired Go version
 
       - name: Build
-        run: go build -v ./...
+        run: go build -v ./...
+
+      - name: Test
+        run: go test -v ./...

cmd/cointoss.go

@@ -2,47 +2,13 @@ package cmd
 
 import (
 	"fmt"
-	"math/rand"
 	"strings"
-	"time"
+
+	"github.com/chrisreddington/gh-game/internal/cointoss" // adjust import path as needed
 
 	"github.com/spf13/cobra"
 )
 
-// Helper functions
-func tossCoin() string {
-	rand.Seed(time.Now().UnixNano())
-	if rand.Float32() < 0.5 {
-		return "heads"
-	}
-	return "tails"
-}
-
-func validateGuess(guess string) error {
-	guess = strings.ToLower(strings.TrimSpace(guess))
-	if guess != "heads" && guess != "tails" {
-		return fmt.Errorf("guess must be either 'heads' or 'tails'")
-	}
-	return nil
-}
-
-func getNextGuess() (string, bool) {
-	fmt.Print("Play again? Enter 'heads' or 'tails' (or 'quit' to end): ")
-	var answer string
-	fmt.Scanln(&answer)
-
-	if strings.ToLower(strings.TrimSpace(answer)) == "quit" {
-		return "", false
-	}
-
-	if err := validateGuess(answer); err != nil {
-		fmt.Println(err)
-		return getNextGuess()
-	}
-
-	return strings.ToLower(strings.TrimSpace(answer)), true
-}
-
 var cointossCmd = &cobra.Command{
 	Use:   "cointoss [guess]",
 	Short: "Toss a coin",
@@ -51,22 +17,22 @@ var cointossCmd = &cobra.Command{
 		if len(args) != 1 {
 			return fmt.Errorf("requires exactly 1 argument (guess)")
 		}
-		return validateGuess(args[0])
+		return cointoss.ValidateGuess(args[0])
 	},
 	Run: func(cmd *cobra.Command, args []string) {
 		guess := strings.ToLower(strings.TrimSpace(args[0]))
 		streak := 0
 		keepPlaying := true
 
 		for keepPlaying {
-			result := tossCoin()
+			result := cointoss.TossCoin()
 			fmt.Printf("The coin shows: %s!\n", strings.Title(result))
 
 			if guess == result {
 				streak++
 				fmt.Printf("Correct! Streak: %d\n", streak)
 				var continuePlay bool
-				guess, continuePlay = getNextGuess()
+				guess, continuePlay = cointoss.GetNextGuess()
 				keepPlaying = continuePlay
 			} else {
 				fmt.Printf("Game Over! Final streak: %d\n", streak)

internal/cointoss/cointoss.go

@@ -0,0 +1,41 @@
+package cointoss
+
+import (
+	"fmt"
+	"math/rand"
+	"strings"
+	"time"
+)
+
+func TossCoin() string {
+	rand.Seed(time.Now().UnixNano())
+	if rand.Float32() < 0.5 {
+		return "heads"
+	}
+	return "tails"
+}
+
+func ValidateGuess(guess string) error {
+	guess = strings.ToLower(strings.TrimSpace(guess))
+	if guess != "heads" && guess != "tails" {
+		return fmt.Errorf("guess must be either 'heads' or 'tails'")
+	}
+	return nil
+}
+
+func GetNextGuess() (string, bool) {
+	fmt.Print("Play again? Enter 'heads' or 'tails' (or 'quit' to end): ")
+	var answer string
+	fmt.Scanln(&answer)
+
+	if strings.ToLower(strings.TrimSpace(answer)) == "quit" {
+		return "", false
+	}
+
+	if err := ValidateGuess(answer); err != nil {
+		fmt.Println(err)
+		return GetNextGuess()
+	}
+
+	return strings.ToLower(strings.TrimSpace(answer)), true
+}

internal/cointoss/cointoss_test.go

@@ -0,0 +1,31 @@
+package cointoss
+
+import (
+	"testing"
+)
+
+func TestValidateGuess(t *testing.T) {
+	validGuesses := []string{"heads", "heads ", " HEADS", "tails", "TAILS", " tails "}
+	invalidGuesses := []string{"", "foo", "123", "heds", "taol"}
+
+	for _, guess := range validGuesses {
+		if err := ValidateGuess(guess); err != nil {
+			t.Errorf("ValidateGuess(%q) returned error: %v, expected nil", guess, err)
+		}
+	}
+
+	for _, guess := range invalidGuesses {
+		if err := ValidateGuess(guess); err == nil {
+			t.Errorf("ValidateGuess(%q) did not return error, expected error", guess)
+		}
+	}
+}
+
+func TestTossCoin(t *testing.T) {
+	for i := 0; i < 100; i++ {
+		result := TossCoin()
+		if result != "heads" && result != "tails" {
+			t.Errorf("TossCoin() returned unexpected value %q", result)
+		}
+	}
+}