test(deisctl): add example unit tests for help and --version

deisctl/deisctl_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"strings"
+	"testing"
+)
+
+// commandOutput returns stdout for a deisctl command line as a string.
+func commandOutput(args []string) (output string) {
+	old := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	Command(args)
+
+	outC := make(chan string)
+	go func() {
+		var buf bytes.Buffer
+		io.Copy(&buf, r)
+		outC <- buf.String()
+	}()
+
+	w.Close()
+	os.Stdout = old
+	output = <-outC
+	return
+}
+
+// TestHelp tests that deisctl is flexible when being asked to print built-in help.
+func TestHelp(t *testing.T) {
+	allArgs := [][]string{{"-h"}, {"--help"}, {"help"}}
+	out := ""
+	for _, args := range allArgs {
+		out = commandOutput(args)
+		if !strings.Contains(out, "Usage: deisctl <command> [<args>...] [options]") ||
+			!strings.Contains(out, "Commands, use \"deisctl help <command>\" to learn more") {
+			t.Error(out)
+		}
+	}
+}
+
+// TestUsage ensures that deisctl prints a short usage string when no arguments were provided.
+func TestUsage(t *testing.T) {
+	out := commandOutput(nil)
+	if out != "Usage: deisctl <command> [<args>...] [options]\n" {
+		t.Error(out)
+	}
+}
+
+// TestVersion verifies that "deisctl --version" prints the current version string.
+func TestVersion(t *testing.T) {
+	args := []string{"--version"}
+	out := commandOutput(args)
+	if !strings.HasPrefix(out, Version) {
+		t.Error(out)
+	}
+}