Add tests for help command

internal/pkg/conflictless/cli.go

@@ -56,7 +56,7 @@ func argsWithoutTestFlags() []string {
 
 	for _, arg := range os.Args {
 		if strings.HasPrefix(arg, "-test.") {
-			break
+			continue
 		}
 
 		args = append(args, arg)

internal/pkg/conflictless/cli_test.go

@@ -2,6 +2,7 @@ package conflictless_test
 
 import (
 	"errors"
+	"net/url"
 	"os"
 	"os/exec"
 	"testing"
@@ -51,3 +52,66 @@ func TestCLIWithoutArguments(t *testing.T) {
 
 	assert.Equal(t, expectedCode, exitCode, "process exited with %d, want exit status %d", expectedCode, exitCode)
 }
+
+func TestCLIHelp(t *testing.T) {
+	t.Parallel()
+
+	if os.Getenv("TEST_CLI_HELP") != "" {
+		conflictless.CLI()
+
+		return
+	}
+
+	for _, testCase := range []struct {
+		description string
+		args        []string
+		isError     bool
+	}{
+		{"help", []string{"help"}, false},
+		{"help check", []string{"help", "check"}, false},
+		{"help generate", []string{"help", "generate"}, false},
+		{"help unknown", []string{"help", "unknown"}, true},
+	} {
+		// Reinitialise testCase for parallel testing.
+		testCase := testCase
+
+		t.Run(testCase.description, func(t *testing.T) {
+			t.Parallel()
+
+			stdoutFile := createTempFile(t, os.TempDir(), "test-cli-"+url.QueryEscape(testCase.description)+"-stdout")
+			defer os.Remove(stdoutFile.Name())
+
+			stderrFile := createTempFile(t, os.TempDir(), "test-cli-"+url.QueryEscape(testCase.description)+"-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], append([]string{"-test.run=^TestCLIHelp$"}, testCase.args...)...)
+			cmd.Env = append(os.Environ(), "TEST_CLI_HELP=1")
+			cmd.Stdout = stdoutFile
+			cmd.Stderr = stderrFile
+
+			err := cmd.Run()
+
+			if testCase.isError {
+				assert.Error(t, err)
+				assert.IsType(t, new(exec.ExitError), err)
+			} else {
+				assert.NoError(t, err)
+			}
+
+			stderrData, err := os.ReadFile(stderrFile.Name())
+			assert.NoError(t, err)
+
+			stdoutData, err := os.ReadFile(stdoutFile.Name())
+			assert.NoError(t, err)
+
+			if testCase.isError {
+				assert.Empty(t, string(stdoutData))
+				assert.Contains(t, string(stderrData), "Error:")
+			} else {
+				assert.Contains(t, string(stdoutData), "Usage: conflictless")
+				assert.Empty(t, string(stderrData))
+			}
+		})
+	}
+}

internal/pkg/conflictless/help.go

@@ -23,7 +23,6 @@ func help() {
 		usage()
 	default:
 		PrintErrorAndExit(fmt.Sprintf("unknown help topic '%s'", topic), func() {})
-		os.Exit(exitCodeMisuseError)
 	}
 
 	os.Exit(exitCodeSuccess)