Consolidate the testing page with recipes from the cookbook. (#2380)

Author: brianegan

.firebaserc

@@ -10,6 +10,7 @@
     "kw": "kw-flutter-1",
     "kw2": "kw-flutter-2",
     "ft": "flutter-web-staging",
-    "filip": "flutter-website-filiph-staging"
+    "filip": "flutter-website-filiph-staging",
+    "brianegan": "brianegan-flutter-staging"
   }
-}
+}

src/_includes/testing_toc.md

@@ -0,0 +1,19 @@
+{% comment %}
+  Generates a list of testing recipes for the given type. The type corresponds
+  to the name of the directory under cookbook/testing/*.
+  
+  Usage: {% include testing_toc.md type='unit' %}
+{% endcomment -%}
+
+{% assign dir = 'cookbook/testing/' | append: include.type %}
+
+{% assign recipes = site.pages | where_exp:"item", "item.dir contains dir" | sort: 'title' %}
+
+{% for recipe in recipes -%}
+{% comment %}
+  Exclude index pages (all other pages will end in `.html`).
+{% endcomment -%}
+{% if recipe.url contains '.html' -%}
+- [{{ recipe.title }}]({{ recipe.url }})
+{% endif -%}
+{% endfor %}