Squashed get CA derivations building

tests/content-addressed.nix

@@ -0,0 +1,19 @@
+with import ./config.nix;
+
+{ seed ? 0 }:
+# A simple content-addressed derivation.
+# The derivation can be arbitrarily modified by passing a different `seed`,
+# but the output will always be the same
+mkDerivation {
+  name = "simple-content-addressed";
+  buildCommand = ''
+    set -x
+    echo "Building a CA derivation"
+    echo "The seed is ${toString seed}"
+    mkdir -p $out
+    echo "Hello World" > $out/hello
+  '';
+  __contentAddressed = true;
+  outputHashMode = "recursive";
+  outputHashAlgo = "sha256";
+}