all: Refactor to nonglobal Viper, i18n etc.

This is a final rewrite that removes all the global state in Hugo, which also enables
the use if `t.Parallel` in tests.

Updates #2701
Fixes #3016

commands/commandeer.go

@@ -0,0 +1,46 @@
+// Copyright 2017 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 commands
+
+import (
+	"github.com/spf13/hugo/deps"
+	"github.com/spf13/hugo/helpers"
+)
+
+type commandeer struct {
+	*deps.DepsCfg
+	pathSpec   *helpers.PathSpec
+	configured bool
+}
+
+func (c *commandeer) Set(key string, value interface{}) {
+	if c.configured {
+		panic("commandeer cannot be changed")
+	}
+	c.Cfg.Set(key, value)
+}
+
+// PathSpec lazily creates a new PathSpec, as all the paths must
+// be configured before it is created.
+func (c *commandeer) PathSpec() *helpers.PathSpec {
+	c.configured = true
+	if c.pathSpec == nil {
+		c.pathSpec = helpers.NewPathSpec(c.Fs, c.Cfg)
+	}
+	return c.pathSpec
+}
+
+func newCommandeer(cfg *deps.DepsCfg) *commandeer {
+	return &commandeer{DepsCfg: cfg}
+}