Try it:
git clone --single-branch -b hugo-forum-topic-37085 https://github.com/jmooring/hugo-testing hugo-forum-topic-37085
cd hugo-forum-topic-37085
hugo server
content/
├── products/
│ ├── _index.md
│ ├── product-1.md <-- front matter: layout = 'product-1'
│ ├── product-2.md <-- front matter: layout = 'product-2
│ ├── product-3.md <-- front matter: layout = 'product-3'
│ └── product-4.md
└── _index.md
layouts/
├── _default/
│ ├── baseof.html
│ ├── home.html
│ ├── list.html
│ └── single.html
└── products/
├── list.html <-- used by content/products/_index.md
├── product-1.html <-- used by content/products/product-1.md
├── product-2.html <-- used by content/products/product-2.md
├── product-3.html <-- used by content/products/product-3.md
└── single.html <-- used by content/products/product-4.md