feat: add tests for internal packages

internal/inputs/inputs.go

@@ -41,11 +41,5 @@ func ExtractIntPairs(input string) ([]int, []int, error) {
 		right = append(right, rightNum)
 	}
 
-	// Check whether the number of elements in left and right slices are the same
-	// This check is probably not needed
-	if len(left) != len(right) {
-		return nil, nil, fmt.Errorf("Length of left and right slices differ: %d, %d", len(left), len(right))
-	}
-
 	return left, right, nil
 }

internal/inputs/inputs_test.go

@@ -0,0 +1,55 @@
+package inputs
+
+import (
+	"slices"
+	"testing"
+)
+
+func TestExtractIntPairs(t *testing.T) {
+	t.Run("empty input", func(t *testing.T) {
+		input := ``
+		_, _, err := ExtractIntPairs(input)
+
+		if err == nil {
+			t.Errorf("expected an error, didnt get one")
+		}
+	})
+
+	t.Run("invalid line", func(t *testing.T) {
+		input := `123 456 789`
+		_, _, err := ExtractIntPairs(input)
+
+		if err == nil {
+			t.Errorf("expected an error, didnt get one")
+		}
+	})
+
+	t.Run("invalid left column", func(t *testing.T) {
+		input := `abc 123`
+		_, _, err := ExtractIntPairs(input)
+
+		if err == nil {
+			t.Errorf("expected an error, didnt get one")
+		}
+	})
+
+	t.Run("invalid right column", func(t *testing.T) {
+		input := `123 abc`
+		_, _, err := ExtractIntPairs(input)
+
+		if err == nil {
+			t.Errorf("expected an error, didnt get one")
+		}
+	})
+
+	t.Run("test slice content", func(t *testing.T) {
+		input := "111 222\n333 444"
+		leftWant := []int{111, 333}
+		rightWant := []int{222, 444}
+		leftGot, rightGot, _ := ExtractIntPairs(input)
+
+		if !slices.Equal(leftGot, leftWant) || !slices.Equal(rightGot, rightWant) {
+			t.Errorf("Expected %v, %v, got %v, %v", leftWant, leftGot, rightWant, rightGot)
+		}
+	})
+}

internal/math/math_test.go

@@ -0,0 +1,25 @@
+package math
+
+import "testing"
+
+func TestAbs(t *testing.T) {
+	tests := []struct {
+		name  string
+		input int
+		want  int
+	}{
+		{name: "positive number", input: 7, want: 7},
+		{name: "negative number", input: -5, want: 5},
+		{name: "zero", input: 0, want: 0},
+		{name: "minus zero", input: -0, want: 0},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := Abs(tt.input)
+			if got != tt.want {
+				t.Errorf("got %d, want %d", got, tt.want)
+			}
+		})
+	}
+}