Scale functions with namespace option

Allows alerts to trigger functions to scale when they
also have an optional namespace set.

Tested e2e with Kubernetes 1.15 and a non-default namespace.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

gateway/handlers/namespaces_test.go

@@ -0,0 +1,45 @@
+// Copyright (c) Alex Ellis 2017. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+package handlers
+
+import "testing"
+
+func Test_getNamespace_Default(t *testing.T) {
+	root, ns := getNamespace("openfaas-fn", "figlet.openfaas-fn")
+	wantRoot := "figlet"
+	wantNs := "openfaas-fn"
+
+	if root != wantRoot {
+		t.Errorf("function root: want %s, got %s", wantRoot, root)
+	}
+	if ns != wantNs {
+		t.Errorf("function ns: want %s, got %s", wantNs, ns)
+	}
+}
+
+func Test_getNamespace_Override(t *testing.T) {
+	root, ns := getNamespace("fn", "figlet.fn")
+	wantRoot := "figlet"
+	wantNs := "fn"
+
+	if root != wantRoot {
+		t.Errorf("function root: want %s, got %s", wantRoot, root)
+	}
+	if ns != wantNs {
+		t.Errorf("function ns: want %s, got %s", wantNs, ns)
+	}
+}
+
+func Test_getNamespace_Empty(t *testing.T) {
+	root, ns := getNamespace("", "figlet")
+	wantRoot := "figlet"
+	wantNs := ""
+
+	if root != wantRoot {
+		t.Errorf("function root: want %s, got %s", wantRoot, root)
+	}
+	if ns != wantNs {
+		t.Errorf("function ns: want %s, got %s", wantNs, ns)
+	}
+}