attempt to CI the nix tests

.circleci/config.yml

@@ -15,6 +15,33 @@
 version: 2
 
 jobs:
+  test:
+    docker:
+      - image: "nixos/nix:2.2.1"
+    steps:
+      - run:
+          name: "Install CA Certificates"
+          command: |
+            # Required for cache and artifact interactions.  Though we use a
+            # nix image, it's actually an alpine base...  The CircleCI cache
+            # management and artifact uploader doesn't know how to use the nix
+            # ca bundle we could install.
+            apk update
+            apk add ca-certificates
+
+      - run:
+          name: "Install Git"
+          command: |
+            # Required for the checkout step
+            nix-env -i git openssh
+
+      - "checkout"
+
+      - run:
+          name: "Run Tests"
+          command: |
+            nix-build nixos/tests.nix
+
   build:
     docker:
       - image: "nixos/nix:2.2.1"
@@ -59,4 +86,5 @@ workflows:
   version: 2
   everything:
     jobs:
+      - "test"
       - "build"