Test admxgen main package

These tests also cover the commands package as we exercise the main
function directly.

cmd/admxgen/main_test.go

@@ -0,0 +1,111 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type myApp struct {
+	runError         bool
+	usageErrorReturn bool
+}
+
+func (a *myApp) Run() error {
+	if a.runError {
+		return errors.New("Error requested")
+	}
+	return nil
+}
+
+func (a myApp) UsageError() bool {
+	return a.usageErrorReturn
+}
+
+func TestRun(t *testing.T) {
+	tests := map[string]struct {
+		runError         bool
+		usageErrorReturn bool
+
+		wantReturnCode int
+	}{
+		"Run and exit successfully":              {},
+		"Run and return error":                   {runError: true, wantReturnCode: 1},
+		"Run and return usage error":             {usageErrorReturn: true, runError: true, wantReturnCode: 2},
+		"Run and usage error only does not fail": {usageErrorReturn: true},
+	}
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			a := myApp{
+				runError:         tc.runError,
+				usageErrorReturn: tc.usageErrorReturn,
+			}
+
+			var rc int
+			wait := make(chan struct{})
+			go func() {
+				rc = run(&a)
+				close(wait)
+			}()
+
+			<-wait
+
+			require.Equal(t, tc.wantReturnCode, rc, "Return expected code")
+		})
+	}
+}
+
+func TestMainApp(t *testing.T) {
+	if os.Getenv("ADSYS_CALL_MAIN") != "" {
+		main()
+		return
+	}
+
+	// #nosec G204: this is only for tests, under controlled args
+	cmd := exec.Command(os.Args[0], "help", "-test.run=TestMainApp")
+	cmd.Env = append(os.Environ(), "ADSYS_CALL_MAIN=1")
+	out, err := cmd.CombinedOutput()
+
+	require.Contains(t, string(out),
+		"Generate ADMX and intermediary working files from a list of policy definition files.",
+		"Main function should print the help message",
+	)
+	require.NoError(t, err, "Main should not return an error")
+}
+
+func TestAppUsage(t *testing.T) {
+	tests := map[string]struct {
+		args []string
+
+		wantUsageError bool
+	}{
+		"Expand with correct arguments": {args: []string{"expand", "source", "dest"}},
+		"Admx with correct arguments":   {args: []string{"admx", "categories.yaml", "source", "dest"}},
+		"Doc with correct arguments":    {args: []string{"doc", "categories.yaml", "source", "dest"}},
+
+		"Error when command is called with wrong arguments": {args: []string{"not_a_command"}, wantUsageError: true},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			if os.Getenv("ADSYS_CALL_MAIN") != "" {
+				main()
+				return
+			}
+
+			args := append([]string{os.Args[0]}, tc.args...)
+			args = append(args, "-test.run=TestMainApp")
+
+			// #nosec G204: this is only for tests, under controlled args
+			cmd := exec.Command(args[0], args[1:]...)
+			cmd.Env = append(os.Environ(), "ADSYS_CALL_MAIN=1")
+
+			err := cmd.Run()
+			require.Error(t, err, "Main should return an error")
+			require.Equal(t, tc.wantUsageError, cmd.ProcessState.ExitCode() == 2, "Main should return expected code")
+		})
+	}
+}