Add tests for cli

internal/pkg/conflictless/cli.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"strings"
 )
 
 const (
@@ -50,11 +51,27 @@ func CLI() {
 	}
 }
 
+func argsWithoutTestFlags() []string {
+	args := []string{}
+
+	for _, arg := range os.Args {
+		if strings.HasPrefix(arg, "-test.") {
+			break
+		}
+
+		args = append(args, arg)
+	}
+
+	return args
+}
+
 func parseCLIFlags(cfg *Config) {
 	flag.Usage = usage
 
-	if len(os.Args) > argIdxCommand {
-		cfg.Flags.Command = os.Args[argIdxCommand]
+	args := argsWithoutTestFlags()
+
+	if len(args) > argIdxCommand {
+		cfg.Flags.Command = args[argIdxCommand]
 	}
 
 	var cmd *flag.FlagSet
@@ -78,7 +95,7 @@ func parseCLIFlags(cfg *Config) {
 	}
 
 	if cmd != nil {
-		err := cmd.Parse(os.Args[2:])
+		err := cmd.Parse(args[2:])
 		if err != nil {
 			panic(err)
 		}

internal/pkg/conflictless/cli_test.go

@@ -0,0 +1,53 @@
+package conflictless_test
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/ypjama/conflictless-keepachangelog/internal/pkg/conflictless"
+)
+
+func TestCLIWithoutArguments(t *testing.T) {
+	t.Parallel()
+
+	if os.Getenv("TEST_CLI_WITHOUT_ARGUMENTS") == "1" {
+		conflictless.CLI()
+
+		return
+	}
+
+	stdoutFile := createTempFile(t, os.TempDir(), "test-cli-without-args-stdout")
+	defer os.Remove(stdoutFile.Name())
+
+	stderrFile := createTempFile(t, os.TempDir(), "test-cli-without-args-stderr")
+	defer os.Remove(stderrFile.Name())
+
+	//nolint:gosec // this is a test package so G204 doesn't really matter here.
+	cmd := exec.Command(os.Args[0], "-test.run=^TestCLIWithoutArguments$")
+
+	cmd.Env = append(os.Environ(), "TEST_CLI_WITHOUT_ARGUMENTS=1")
+	cmd.Stdout = stdoutFile
+	cmd.Stderr = stderrFile
+	err := cmd.Run()
+
+	assert.IsType(t, new(exec.ExitError), err)
+
+	exitErr := new(*exec.ExitError)
+	errors.As(err, exitErr)
+
+	expectedCode := 2
+	exitCode := (*exitErr).ExitCode()
+
+	stdoutData, err := os.ReadFile(stdoutFile.Name())
+	assert.NoError(t, err)
+	assert.Empty(t, stdoutData)
+
+	stderrData, err := os.ReadFile(stderrFile.Name())
+	assert.NoError(t, err)
+	assert.Contains(t, string(stderrData), "Usage: conflictless <command> [flags]")
+
+	assert.Equal(t, expectedCode, exitCode, "process exited with %d, want exit status %d", expectedCode, exitCode)
+}

internal/pkg/conflictless/help.go

@@ -7,8 +7,11 @@ import (
 
 func help() {
 	var topic string
-	if len(os.Args) > argIdxHelpTopic {
-		topic = os.Args[argIdxHelpTopic]
+
+	args := argsWithoutTestFlags()
+
+	if len(args) > argIdxHelpTopic {
+		topic = args[argIdxHelpTopic]
 	}
 
 	switch topic {