Current round of tests pass, but filter function is failing to include when platform match in use.

pkgs/development/ruby-modules/bundler-env/basic.nix

@@ -20,15 +20,13 @@
 , ...
 }@args:
 
-with (
-builtins.trace "basic functions"
-import ./functions.nix { inherit lib ruby gemConfig groups; });
+with  import ./functions.nix { inherit lib gemConfig; };
 
 let
 
   importedGemset = import gemset;
 
-  filteredGemset = filterGemset importedGemset;
+  filteredGemset = filterGemset { inherit ruby groups; } importedGemset;
 
   configuredGemset = lib.flip lib.mapAttrs filteredGemset (name: attrs:
     applyGemConfigs (attrs // { inherit ruby; gemName = name; })
@@ -66,13 +64,12 @@ let
 
   buildGem = name: attrs: (
     let
-      gemAttrs = composeGemAttrs gems name attrs;
+      gemAttrs = composeGemAttrs ruby gems name attrs;
     in
     if gemAttrs.type == "path" then
       pathDerivation gemAttrs
     else
-      builtins.trace (lib.showVal (gemAttrs.ruby or "def ruby"))
-        buildRubyGem gemAttrs
+      buildRubyGem gemAttrs
   );
 
   envPaths = lib.attrValues gems ++ lib.optional (!hasBundler) bundler;

pkgs/development/ruby-modules/bundler-env/functions.nix

@@ -1,17 +1,19 @@
-{ lib, ruby, groups, gemConfig, ... }:
-builtins.trace (if ruby.stubbed or false then "functions has stubbed ruby" else "functions has live ruby")
+{ lib, gemConfig, ... }:
 rec {
-  filterGemset = gemset: lib.filterAttrs (name: attrs: platformMatches attrs && groupMatches attrs) gemset;
+  filterGemset = {ruby, groups,...}@env: gemset: lib.filterAttrs (name: attrs: platformMatches ruby attrs && groupMatches groups attrs) gemset;
 
-  platformMatches = attrs: (
+  platformMatches = {rubyEngine, version, ...}@ruby: attrs: (
   !(attrs ? "platforms") ||
+  builtins.trace "ruby engine: ${rubyEngine}"
+  builtins.trace "ruby version ${version.majMin}"
     builtins.any (platform:
-      platform.engine == ruby.rubyEngine &&
-        (!(platform ? "version") || platform.version == ruby.version.majMin)
+    builtins.trace "checking: ${platform.engine}/${platform.version}"
+      platform.engine == rubyEngine &&
+        (!(platform ? "version") || platform.version == version.majMin)
     ) attrs.platforms
   );
 
-  groupMatches = attrs: (
+  groupMatches = groups: attrs: (
   !(attrs ? "groups") ||
     builtins.any (gemGroup: builtins.any (group: group == gemGroup) groups) attrs.groups
   );
@@ -45,7 +47,7 @@ rec {
         };
     in res;
 
-  composeGemAttrs = gems: name: attrs: ((removeAttrs attrs ["source" "platforms"]) // attrs.source // {
+  composeGemAttrs = ruby: gems: name: attrs: ((removeAttrs attrs ["source" "platforms"]) // attrs.source // {
     inherit ruby;
     gemName = name;
     gemPath = map (gemName: gems."${gemName}") (attrs.dependencies or []);

pkgs/development/ruby-modules/bundler-env/runtests.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+nix-build -E 'with import <nixpkgs> { }; callPackage ./test.nix {}' --show-trace && cat result

pkgs/development/ruby-modules/bundler-env/test.nix

@@ -18,11 +18,10 @@ let
   };
 
   testConfigs = {
-    groups = ["default"];
+    inherit lib;
     gemConfig =  defaultGemConfig;
-    confFiles = "./testConfs";
   };
-  functions = (import ./functions.nix ({ inherit lib; ruby = stubs.ruby; } // testConfigs));
+  functions = (import ./functions.nix testConfigs);
 
   justName = bundlerEnv {
     name = "test";
@@ -38,7 +37,16 @@ let
   };
 
   results = builtins.concatLists [
-    (test.run "Filter empty gemset" {} (set: functions.filterGemset set == {}))
+    (test.run "Filter empty gemset" {} (set: functions.filterGemset {inherit ruby; groups = ["default"]; } set == {}))
+    ( let gemSet = { test = { groups = ["x" "y"]; }; };
+      in
+      test.run "Filter matches a group" gemSet (set: functions.filterGemset {inherit ruby; groups = ["y" "z"];} set == gemSet))
+    ( let gemSet = { test = { platforms = [{engine = ruby.rubyEngine; version = ruby.version;}]; }; };
+      in
+      test.run "Filter matches on platform" gemSet (set: functions.filterGemset {inherit ruby; groups = [];} set == gemSet))
+    ( let gemSet = { test = { groups = ["x" "y"]; }; };
+      in
+      test.run "Filter excludes based on groups" gemSet (set: functions.filterGemset {inherit ruby; groups = ["a" "b"];} set == {}))
     (test.run "bundlerEnv { name }" justName {
       name = should.equal "test";
     })

pkgs/development/ruby-modules/gem/default.nix

@@ -74,8 +74,6 @@ let
 
 in
 
-builtins.trace (gemName)
-builtins.trace (stdenv.stubbed or false)
 stdenv.mkDerivation (attrs // {
   inherit ruby;
   inherit doCheck;