assets builder tools (#39)

Reviewed-on: #39
Reviewed-by: xtul <mpiasecki720@protonmail.com>

internal/assets/run_test.go

@@ -0,0 +1,26 @@
+package assets
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func env(string) string { return "" }
+
+func TestRunNoArgsIsUsage(t *testing.T) {
+	var out, errw bytes.Buffer
+	if code := Run(nil, &out, &errw, env); code != exitUsage {
+		t.Fatalf("no args exit = %d, want %d", code, exitUsage)
+	}
+	if !strings.Contains(errw.String(), "usage") {
+		t.Fatalf("no args should print usage, got: %q", errw.String())
+	}
+}
+
+func TestRunUnknownSubcommandIsUsage(t *testing.T) {
+	var out, errw bytes.Buffer
+	if code := Run([]string{"frobnicate"}, &out, &errw, env); code != exitUsage {
+		t.Fatalf("unknown subcommand exit = %d, want %d", code, exitUsage)
+	}
+}