Add breaking tests for "map read and map write in templates"

The fix upstream in Go was reverted, so we apply a temporary patch for this in Hugo.

Updates #7293

hugolib/embedded_templates_test.go

@@ -15,6 +15,8 @@ package hugolib
 
 import (
 	"testing"
+
+	qt "github.com/frankban/quicktest"
 )
 
 func TestInternalTemplatesImage(t *testing.T) {
@@ -77,3 +79,40 @@ title: My Site
 <meta itemprop="image" content="https://example.org/siteimg1.jpg"/>
 `)
 }
+
+// Just some simple test of the embedded templates to avoid
+// https://github.com/gohugoio/hugo/issues/4757 and similar.
+func TestEmbeddedTemplates(t *testing.T) {
+	t.Parallel()
+
+	c := qt.New(t)
+	c.Assert(true, qt.Equals, true)
+
+	home := []string{"index.html", `
+GA:
+{{ template "_internal/google_analytics.html" . }}
+
+GA async:
+
+{{ template "_internal/google_analytics_async.html" . }}
+
+Disqus:
+
+{{ template "_internal/disqus.html" . }}
+
+`}
+
+	b := newTestSitesBuilder(t)
+	b.WithSimpleConfigFile().WithTemplatesAdded(home...)
+
+	b.Build(BuildCfg{})
+
+	// Gheck GA regular and async
+	b.AssertFileContent("public/index.html",
+		"'anonymizeIp', true",
+		"'script','https://www.google-analytics.com/analytics.js','ga');\n\tga('create', 'ga_id', 'auto')",
+		"<script async src='https://www.google-analytics.com/analytics.js'>")
+
+	// Disqus
+	b.AssertFileContent("public/index.html", "\"disqus_shortname\" + '.disqus.com/embed.js';")
+}