Add some unit tests to the node and swarm cli code

Start work on adding unit tests to our cli code in order to have to
write less costly integration test.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

pkg/testutil/assert/assert.go

@@ -7,6 +7,7 @@ import (
 	"reflect"
 	"runtime"
 	"strings"
+	"unicode"
 
 	"github.com/davecgh/go-spew/spew"
 )
@@ -25,6 +26,25 @@ func Equal(t TestingT, actual, expected interface{}) {
 	}
 }
 
+// EqualNormalizedString compare the actual value to the expected value after applying the specified
+// transform function. It fails the test if these two transformed string are not equal.
+// For example `EqualNormalizedString(t, RemoveSpace, "foo\n", "foo")` wouldn't fail the test as
+// spaces (and thus '\n') are removed before comparing the string.
+func EqualNormalizedString(t TestingT, transformFun func(rune) rune, actual, expected string) {
+	if strings.Map(transformFun, actual) != strings.Map(transformFun, expected) {
+		fatal(t, "Expected '%v' got '%v'", expected, expected, actual, actual)
+	}
+}
+
+// RemoveSpace returns -1 if the specified runes is considered as a space (unicode)
+// and the rune itself otherwise.
+func RemoveSpace(r rune) rune {
+	if unicode.IsSpace(r) {
+		return -1
+	}
+	return r
+}
+
 //EqualStringSlice compares two slices and fails the test if they do not contain
 // the same items.
 func EqualStringSlice(t TestingT, actual, expected []string) {