Add a test for nix flake show

tests/flakes/common.sh

@@ -20,6 +20,10 @@ writeSimpleFlake() {
       foo = import ./simple.nix;
       default = foo;
     };
+    packages.someOtherSystem = rec {
+      foo = import ./simple.nix;
+      default = foo;
+    };
 
     # To test "nix flake init".
     legacyPackages.x86_64-linux.hello = import ./simple.nix;

tests/flakes/show.sh

@@ -0,0 +1,39 @@
+source ./common.sh
+
+flakeDir=$TEST_ROOT/flake
+mkdir -p "$flakeDir"
+
+writeSimpleFlake "$flakeDir"
+cd "$flakeDir"
+
+
+# By default: Only show the packages content for the current system and no
+# legacyPackages at all
+nix flake show --json > show-output.json
+nix eval --impure --expr '
+let show_output = builtins.fromJSON (builtins.readFile ./show-output.json);
+in
+assert show_output.packages.someOtherSystem.default == {};
+assert show_output.packages.${builtins.currentSystem}.default.name == "simple";
+assert show_output.legacyPackages.${builtins.currentSystem} == {};
+true
+'
+
+# With `--all-systems`, show the packages for all systems
+nix flake show --json --all-systems > show-output.json
+nix eval --impure --expr '
+let show_output = builtins.fromJSON (builtins.readFile ./show-output.json);
+in
+assert show_output.packages.someOtherSystem.default.name == "simple";
+assert show_output.legacyPackages.${builtins.currentSystem} == {};
+true
+'
+
+# With `--legacy`, show the legacy packages
+nix flake show --json --legacy > show-output.json
+nix eval --impure --expr '
+let show_output = builtins.fromJSON (builtins.readFile ./show-output.json);
+in
+assert show_output.legacyPackages.${builtins.currentSystem}.hello.name == "simple";
+true
+'

tests/local.mk

@@ -113,6 +113,7 @@ nix_tests = \
   store-ping.sh \
   fetchClosure.sh \
   completions.sh \
+  flakes/show.sh \
   impure-derivations.sh \
   path-from-hash-part.sh \
   toString-path.sh