Write the chain on separate lines.

.github/workflows/build_release.yaml

@@ -17,9 +17,9 @@ jobs:
         with:
           go-version: '>=1.22.1'
       - name: release-build-windows
-        run: GOOS=windows GOARCH=amd64 go build -o bin/collatz-${{  github.ref_name }}-windows-amd64.exe
+        run: GOOS=windows GOARCH=amd64 go build -ldflags "-s -w" -o bin/collatz-${{  github.ref_name }}-windows-amd64.exe
       - name: release-build-linux
-        run: GOOS=linux GOARCH=amd64 go build -o bin/collatz-${{  github.ref_name }}-linux-amd64
+        run: GOOS=linux GOARCH=amd64 go build -ldflags "-s -w" -o bin/collatz-${{  github.ref_name }}-linux-amd64
       - name: Release
         uses: https://gitea.com/actions/release-action@main
         with:

.github/workflows/run_tests.yaml

@@ -0,0 +1,22 @@
+name: Run Tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v2
+
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '^1.22.1'
+
+      - name: Run tests
+        run: go test ./...

.gitignore

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

README.md

@@ -0,0 +1 @@
+Run with `go run collatz.go 1234` or download the executable and pass a number `collatz 1234`.

collatz.go

@@ -2,10 +2,34 @@ package main
 
 import (
 	"collatz/collatz"
-	"collatz/io"
+	"collatz/parsing"
+	"log"
+	"strings"
 )
 
 func main() {
-	calculator := collatz.NewCalculator(new(io.Cliargs))
+	sequence, err := runCollatz()
-	calculator.Collatz()
+	if err != nil {
+		log.Fatalf("Error calculating Collatz: %v", err)
+	}
+	printSequence(sequence)
+}
+
+func printSequence(sequence collatz.Sequence) {
+	builder := new(strings.Builder)
+	log.Printf("Collatz sequence with %d iterations:", sequence.Iterations)
+	for i, num := range sequence.Sequence {
+		if i != 0 {
+			builder.WriteString("\n-> ")
+		}
+		builder.WriteString(num.String())
+	}
+	log.Println(builder.String())
+}
+
+func runCollatz() (collatz.Sequence, error) {
+	parser := new(parsing.Cliargs)
+	calculator := collatz.NewCalculator(parser)
+	sequence, err := calculator.CalculateCollatz()
+	return sequence, err
 }

collatz/calculator.go

@@ -1,53 +1,61 @@
 package collatz
 
 import (
-	"collatz/io"
+	"collatz/parsing"
 	"fmt"
-	"log"
 	"math/big"
 )
 
 type Calculator struct {
-	parser *io.Cliargs
+	parser   parsing.Parser
-	three  *big.Int
+	three    *big.Int
-	two    *big.Int
+	two      *big.Int
-	one    *big.Int
+	one      *big.Int
+	sequence Sequence
+}
+type Sequence struct {
+	Iterations int
+	Sequence   []*big.Int
 }
 
-func NewCalculator(parser *io.Cliargs) Calculator {
+func NewCalculator(parser parsing.Parser) *Calculator {
-	r := Calculator{
+	r := &Calculator{
 		parser: parser,
-		three:  new(big.Int).SetInt64(3),
+		three:  big.NewInt(3),
-		two:    new(big.Int).SetInt64(2),
+		two:    big.NewInt(2),
-		one:    new(big.Int).SetInt64(1),
+		one:    big.NewInt(1),
 	}
 	return r
 }
 
-func (o Calculator) Collatz() {
+func (calc *Calculator) CalculateCollatz() (Sequence, error) {
-	number, err := o.parser.Parse()
+	number, err := calc.parser.Parse()
 	if err != nil {
-		log.Panicf("Couldn't parse input: %s\n", err)
+		return Sequence{}, fmt.Errorf("couldn't parse input: %w", err)
 	}
-	fmt.Print(number.Text(10))
+	calc.sequence = Sequence{Iterations: 0}
-	o.nextNumber(number)
+	calc.sequence.Sequence = append(calc.sequence.Sequence, new(big.Int).Set(number))
-	fmt.Println()
+	err = calc.calculateNextCollatzNumber(*number)
+	if err != nil {
+		return Sequence{}, err
+	}
+	return calc.sequence, nil
 }
 
-func (o Calculator) nextNumber(in *big.Int) {
+func (calc *Calculator) calculateNextCollatzNumber(in big.Int) error {
-	if in.Cmp(o.one) < 0 {
+	if in.Cmp(calc.one) < 0 {
-		log.Panicln("Must be greater than 0")
+		return fmt.Errorf("must be greater than 0")
 	}
-	if in.Cmp(o.one) == 0 {
+	if in.Cmp(calc.one) == 0 {
-		return
+		return nil
 	}
 	var newNumber *big.Int
-	if new(big.Int).And(in, o.one).Cmp(o.one) == 0 {
+	if new(big.Int).And(&in, calc.one).Cmp(calc.one) == 0 {
-		newNumber = new(big.Int).Add(new(big.Int).Mul(in, o.three), o.one)
+		newNumber = new(big.Int).Add(new(big.Int).Mul(&in, calc.three), calc.one)
 	} else {
-		newNumber = new(big.Int).Div(in, o.two)
+		newNumber = new(big.Int).Div(&in, calc.two)
 	}
-
+	calc.sequence.Iterations++
-	fmt.Printf(" -> %s", newNumber.Text(10))
+	calc.sequence.Sequence = append(calc.sequence.Sequence, newNumber)
-	o.nextNumber(newNumber)
+	return calc.calculateNextCollatzNumber(*newNumber)
 }

collatz/calculator_test.go

@@ -0,0 +1,48 @@
+package collatz
+
+import (
+	"math/big"
+	"testing"
+)
+
+type MockParser struct {
+	value *big.Int
+}
+
+func (m *MockParser) Parse() (*big.Int, error) {
+	return m.value, nil
+}
+
+func TestNewCalculator(t *testing.T) {
+	parser := &MockParser{}
+	calculator := NewCalculator(parser)
+
+	if calculator.parser != parser {
+		t.Errorf("Expected parser to be %v, got %v", parser, calculator.parser)
+	}
+
+	if calculator.one.Cmp(big.NewInt(1)) != 0 {
+		t.Errorf("Expected one to be 1, got %v", calculator.one)
+	}
+
+	if calculator.two.Cmp(big.NewInt(2)) != 0 {
+		t.Errorf("Expected two to be 2, got %v", calculator.two)
+	}
+
+	if calculator.three.Cmp(big.NewInt(3)) != 0 {
+		t.Errorf("Expected three to be 3, got %v", calculator.three)
+	}
+}
+
+func TestCalculateCollatz(t *testing.T) {
+	parser := &MockParser{value: big.NewInt(6)}
+	calculator := NewCalculator(parser)
+
+	sequence, err := calculator.CalculateCollatz()
+	if err != nil {
+		t.Errorf("Expected no error, got %v", err)
+	}
+	if sequence.Iterations != 8 {
+		t.Errorf("Expected 8 iterations, got %v", sequence.Iterations)
+	}
+}

parsing/cliargs.go

@@ -1,4 +1,4 @@
-package io
+package parsing
 
 import (
 	"errors"
@@ -7,7 +7,6 @@ import (
 )
 
 type Cliargs struct {
-	value *big.Int
 }
 
 func (arg *Cliargs) Parse() (*big.Int, error) {
@@ -19,10 +18,5 @@ func (arg *Cliargs) Parse() (*big.Int, error) {
 	if !success {
 		return nil, errors.New("argument is not an integer")
 	}
-	arg.value = num
 	return num, nil
 }
-
-func (arg *Cliargs) GetNumber() *big.Int {
-	return arg.value
-}

parsing/cliargs_test.go

@@ -0,0 +1,44 @@
+package parsing
+
+import (
+	"math/big"
+	"os"
+	"testing"
+)
+
+func TestCliargs_Parse(t *testing.T) {
+	tests := []struct {
+		name    string
+		args    []string
+		want    *big.Int
+		wantErr bool
+	}{
+		{
+			name:    "Test with valid integer",
+			args:    []string{"", "10"}, // the first argument is the program name
+			want:    big.NewInt(10),
+			wantErr: false,
+		},
+		{
+			name:    "Test with non-integer",
+			args:    []string{"", "abc"}, // the first argument is the program name
+			want:    nil,
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			os.Args = tt.args
+			parser := &Cliargs{}
+			got, err := parser.Parse()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Parse() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr && got.Cmp(tt.want) != 0 {
+				t.Errorf("Parse() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

parsing/interface.go

@@ -0,0 +1,7 @@
+package parsing
+
+import "math/big"
+
+type Parser interface {
+	Parse() (*big.Int, error)
+}