Test baseNameOf behaviour on the root of a flake

tests/functional/flakes/common.sh

@@ -23,6 +23,8 @@ writeSimpleFlake() {
     legacyPackages.$system.hello = import ./simple.nix;
 
     parent = builtins.dirOf ./.;
+
+    baseName = builtins.baseNameOf ./.;
   };
 }
 EOF

tests/functional/flakes/flakes.sh

@@ -234,6 +234,9 @@ nix build -o "$TEST_ROOT/result" --expr "(builtins.getFlake \"git+file://$flake1
 # Regression test for dirOf on the root of the flake.
 [[ $(nix eval --json flake1#parent) = \""$NIX_STORE_DIR"\" ]]
 
+# Regression test for baseNameOf on the root of the flake.
+[[ $(nix eval --raw flake1#baseName) =~ ^[a-z0-9]*-source$ ]]
+
 # Building a flake with an unlocked dependency should fail in pure mode.
 (! nix build -o "$TEST_ROOT/result" flake2#bar --no-registries)
 (! nix build -o "$TEST_ROOT/result" flake2#bar --no-use-registries)