Add Hugo Piper with SCSS support and much more

Before this commit, you would have to use page bundles to do image processing etc. in Hugo.

This commit adds

* A new `/assets` top-level project or theme dir (configurable via `assetDir`)
* A new template func, `resources.Get` which can be used to "get a resource" that can be further processed.

This means that you can now do this in your templates (or shortcodes):

```bash
{{ $sunset := (resources.Get "images/sunset.jpg").Fill "300x200" }}
```

This also adds a new `extended` build tag that enables powerful SCSS/SASS support with source maps. To compile this from source, you will also need a C compiler installed:

```
HUGO_BUILD_TAGS=extended mage install
```

Note that you can use output of the SCSS processing later in a non-SCSSS-enabled Hugo.

The `SCSS` processor is a _Resource transformation step_ and it can be chained with the many others in a pipeline:

```bash
{{ $css := resources.Get "styles.scss" | resources.ToCSS | resources.PostCSS | resources.Minify | resources.Fingerprint }}
<link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen">
```

The transformation funcs above have aliases, so it can be shortened to:

```bash
{{ $css := resources.Get "styles.scss" | toCSS | postCSS | minify | fingerprint }}
<link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen">
```

A quick tip would be to avoid the fingerprinting part, and possibly also the not-superfast `postCSS` when you're doing development, as it allows Hugo to be smarter about the rebuilding.

Documentation will follow, but have a look at the demo repo in https://github.com/bep/hugo-sass-test

New functions to create `Resource` objects:

* `resources.Get` (see above)
* `resources.FromString`: Create a Resource from a string.

New `Resource` transformation funcs:

* `resources.ToCSS`: Compile `SCSS` or `SASS` into `CSS`.
* `resources.PostCSS`: Process your CSS with PostCSS. Config file support (project or theme or passed as an option).
* `resources.Minify`: Currently supports `css`, `js`, `json`, `html`, `svg`, `xml`.
* `resources.Fingerprint`: Creates a fingerprinted version of the given Resource with Subresource Integrity..
* `resources.Concat`: Concatenates a list of Resource objects. Think of this as a poor man's bundler.
* `resources.ExecuteAsTemplate`: Parses and executes the given Resource and data context (e.g. .Site) as a Go template.

Fixes #4381
Fixes #4903
Fixes #4858

1 files changed, 230 insertions, 0 deletions

diff --git a/resource/resource_metadata_test.go b/resource/resource_metadata_test.go
new file mode 100644
index 000000000..85fb25b57
--- /dev/null
+++ b/resource/resource_metadata_test.go
@@ -0,0 +1,230 @@
+// 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 resource
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/media"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAssignMetadata(t *testing.T) {
+	assert := require.New(t)
+	spec := newTestResourceSpec(assert)
+
+	var foo1, foo2, foo3, logo1, logo2, logo3 Resource
+	var resources Resources
+
+	for _, this := range []struct {
+		metaData   []map[string]interface{}
+		assertFunc func(err error)
+	}{
+		{[]map[string]interface{}{
+			{
+				"title": "My Resource",
+				"name":  "My Name",
+				"src":   "*",
+			},
+		}, func(err error) {
+			assert.Equal("My Resource", logo1.Title())
+			assert.Equal("My Name", logo1.Name())
+			assert.Equal("My Name", foo2.Name())
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"title": "My Logo",
+				"src":   "*loGo*",
+			},
+			{
+				"title": "My Resource",
+				"name":  "My Name",
+				"src":   "*",
+			},
+		}, func(err error) {
+			assert.Equal("My Logo", logo1.Title())
+			assert.Equal("My Logo", logo2.Title())
+			assert.Equal("My Name", logo1.Name())
+			assert.Equal("My Name", foo2.Name())
+			assert.Equal("My Name", foo3.Name())
+			assert.Equal("My Resource", foo3.Title())
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"title": "My Logo",
+				"src":   "*loGo*",
+				"params": map[string]interface{}{
+					"Param1": true,
+					"icon":   "logo",
+				},
+			},
+			{
+				"title": "My Resource",
+				"src":   "*",
+				"params": map[string]interface{}{
+					"Param2": true,
+					"icon":   "resource",
+				},
+			},
+		}, func(err error) {
+			assert.NoError(err)
+			assert.Equal("My Logo", logo1.Title())
+			assert.Equal("My Resource", foo3.Title())
+			_, p1 := logo2.Params()["param1"]
+			_, p2 := foo2.Params()["param2"]
+			_, p1_2 := foo2.Params()["param1"]
+			_, p2_2 := logo2.Params()["param2"]
+
+			icon1, _ := logo2.Params()["icon"]
+			icon2, _ := foo2.Params()["icon"]
+
+			assert.True(p1)
+			assert.True(p2)
+
+			// Check merge
+			assert.True(p2_2)
+			assert.False(p1_2)
+
+			assert.Equal("logo", icon1)
+			assert.Equal("resource", icon2)
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"name": "Logo Name #:counter",
+				"src":  "*logo*",
+			},
+			{
+				"title": "Resource #:counter",
+				"name":  "Name #:counter",
+				"src":   "*",
+			},
+		}, func(err error) {
+			assert.NoError(err)
+			assert.Equal("Resource #2", logo2.Title())
+			assert.Equal("Logo Name #1", logo2.Name())
+			assert.Equal("Resource #4", logo1.Title())
+			assert.Equal("Logo Name #2", logo1.Name())
+			assert.Equal("Resource #1", foo2.Title())
+			assert.Equal("Resource #3", foo1.Title())
+			assert.Equal("Name #2", foo1.Name())
+			assert.Equal("Resource #5", foo3.Title())
+
+			assert.Equal(logo2, resources.GetMatch("logo name #1*"))
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"title": "Third Logo #:counter",
+				"src":   "logo3.png",
+			},
+			{
+				"title": "Other Logo #:counter",
+				"name":  "Name #:counter",
+				"src":   "logo*",
+			},
+		}, func(err error) {
+			assert.NoError(err)
+			assert.Equal("Third Logo #1", logo3.Title())
+			assert.Equal("Name #3", logo3.Name())
+			assert.Equal("Other Logo #1", logo2.Title())
+			assert.Equal("Name #1", logo2.Name())
+			assert.Equal("Other Logo #2", logo1.Title())
+			assert.Equal("Name #2", logo1.Name())
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"title": "Third Logo",
+				"src":   "logo3.png",
+			},
+			{
+				"title": "Other Logo #:counter",
+				"name":  "Name #:counter",
+				"src":   "logo*",
+			},
+		}, func(err error) {
+			assert.NoError(err)
+			assert.Equal("Third Logo", logo3.Title())
+			assert.Equal("Name #3", logo3.Name())
+			assert.Equal("Other Logo #1", logo2.Title())
+			assert.Equal("Name #1", logo2.Name())
+			assert.Equal("Other Logo #2", logo1.Title())
+			assert.Equal("Name #2", logo1.Name())
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"name": "third-logo",
+				"src":  "logo3.png",
+			},
+			{
+				"title": "Logo #:counter",
+				"name":  "Name #:counter",
+				"src":   "logo*",
+			},
+		}, func(err error) {
+			assert.NoError(err)
+			assert.Equal("Logo #3", logo3.Title())
+			assert.Equal("third-logo", logo3.Name())
+			assert.Equal("Logo #1", logo2.Title())
+			assert.Equal("Name #1", logo2.Name())
+			assert.Equal("Logo #2", logo1.Title())
+			assert.Equal("Name #2", logo1.Name())
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"title": "Third Logo #:counter",
+			},
+		}, func(err error) {
+			// Missing src
+			assert.Error(err)
+
+		}},
+		{[]map[string]interface{}{
+			{
+				"title": "Title",
+				"src":   "[]",
+			},
+		}, func(err error) {
+			// Invalid pattern
+			assert.Error(err)
+
+		}},
+	} {
+
+		foo2 = spec.newGenericResource(nil, nil, nil, "/b/foo2.css", "foo2.css", media.CSSType)
+		logo2 = spec.newGenericResource(nil, nil, nil, "/b/Logo2.png", "Logo2.png", pngType)
+		foo1 = spec.newGenericResource(nil, nil, nil, "/a/foo1.css", "foo1.css", media.CSSType)
+		logo1 = spec.newGenericResource(nil, nil, nil, "/a/logo1.png", "logo1.png", pngType)
+		foo3 = spec.newGenericResource(nil, nil, nil, "/b/foo3.css", "foo3.css", media.CSSType)
+		logo3 = spec.newGenericResource(nil, nil, nil, "/b/logo3.png", "logo3.png", pngType)
+
+		resources = Resources{
+			foo2,
+			logo2,
+			foo1,
+			logo1,
+			foo3,
+			logo3,
+		}
+
+		this.assertFunc(AssignMetadata(this.metaData, resources...))
+	}
+
+}