Add tpl/site and tpl/hugo

This means that the current `.Site` and ´.Hugo` is available as a globals, so you can do `site.IsServer`, `hugo.Version` etc.

Fixes #5470
Fixes #5467
Fixes #5503

htesting/test_structs.go

@@ -0,0 +1,51 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package htesting
+
+import (
+	"github.com/gohugoio/hugo/common/hugo"
+	"github.com/gohugoio/hugo/langs"
+	"github.com/spf13/viper"
+)
+
+type testSite struct {
+	h hugo.Info
+	l *langs.Language
+}
+
+func (t testSite) Hugo() hugo.Info {
+	return t.h
+}
+
+func (t testSite) IsServer() bool {
+	return false
+}
+
+func (t testSite) Language() *langs.Language {
+	return t.l
+}
+
+// NewTestHugoSite creates a new minimal test site.
+func NewTestHugoSite() hugo.Site {
+	return testSite{
+		h: hugo.NewInfo(),
+		l: langs.NewLanguage("en", newTestConfig()),
+	}
+}
+
+func newTestConfig() *viper.Viper {
+	v := viper.New()
+	v.Set("contentDir", "content")
+	return v
+}