First commit; Added testing; Refactored tests

Author: savannah-ryan

.gitignore

@@ -0,0 +1 @@
+.idea

calc/caclulator_test.go

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+package calc
+
+import "testing"
+
+func TestAddition(t *testing.T) {
+	assertEqual(t, 3, Addition{}.Calculate(1, 2))
+	assertEqual(t, 4, Addition{}.Calculate(2, 2))
+}
+
+func assertEqual(t *testing.T, expected, actual any) {
+	if actual != expected {
+		t.Errorf("Expected: %v -> Actual: %v", expected, actual)
+	}
+}

calc/calculator.go

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+package calc
+
+type Calculator interface{ Calculate(a, b int) int }
+
+type Addition struct {
+	calculator Calculator
+}
+
+func (Addition) Calculate(a, b int) int {
+	return a + b
+}

go.mod

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+module github.com/smartystreets/training-cohort/calc
+
+go 1.22.5

handler.go

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+package main
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+
+	"github.com/smartystreets/training-cohort/calc/calc"
+)
+
+type Handler struct {
+	output     io.Writer
+	calculator calc.Calculator
+}
+
+func NewHandler(output io.Writer, calculator calc.Calculator) *Handler {
+	return &Handler{output: output, calculator: calculator}
+}
+
+func (this *Handler) Handle(values []string) (int, error) {
+	if len(values) != 2 {
+		return 0, errTooFewArgs
+	}
+	a, err := strconv.Atoi(values[0])
+	if err != nil {
+		return 0, errMalformedInput
+	}
+
+	b, err := strconv.Atoi(values[1])
+	if err != nil {
+		return 0, errMalformedInput
+	}
+	return this.calculator.Calculate(a, b), err
+}
+
+var (
+	errTooFewArgs     = fmt.Errorf("Too few arguments provided.")
+	errMalformedInput = fmt.Errorf("Invalid argument type provided.")
+)

handler_test.go

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+package main
+
+import (
+	"errors"
+	"os"
+	"testing"
+
+	"github.com/smartystreets/training-cohort/calcy-lib/calc"
+)
+
+func TestMissingInput(t *testing.T) {
+	var values []string
+	handle := NewHandler(os.Stdout, calc.Addition{})
+	result, err := handle.Handle(values)
+	if result != 0 {
+		t.Error("Expected 0, got ", result)
+	}
+	if !errors.Is(err, errTooFewArgs) {
+		t.Errorf("Expected %s", errTooFewArgs)
+	}
+
+}
+func TestMalformedInput(t *testing.T) {
+	var values []string
+	handle := NewHandler(os.Stdout, calc.Addition{})
+	result, err := handle.Handle(values)
+	if result != 0 {
+		t.Error("Expected 0, got ", result)
+	}
+	if !errors.Is(err, errTooFewArgs) {
+		t.Errorf("Expected %s", errMalformedInput)
+	}
+}
+func TestCorrectInput(t *testing.T) {
+	values := []string{"1", "2"}
+	handle := NewHandler(os.Stdout, calc.Addition{})
+	result, err := handle.Handle(values)
+	if result != 0 {
+		t.Error("Expected 3, got ", result)
+	}
+	if !errors.Is(err, nil) {
+		t.Errorf("Expected %s", "")
+	}
+}

main.go

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+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/smartystreets/training-cohort/calcy-lib/calc"
+)
+
+func main() {
+	handle := NewHandler(os.Stdout, calc.Addition{})
+	result, err := handle.Handle(os.Args[1:])
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("%d\n", result)
+}