Address PR comments

lib/cocoapods/installer.rb

@@ -66,8 +66,8 @@ module Pod
     # @param  [Lockfile] lockfile    @see #lockfile
     #
     def initialize(sandbox, podfile, lockfile = nil)
-      @sandbox  = sandbox || raise(ArgumentError, 'need a sandbox')
-      @podfile  = podfile || raise(ArgumentError, 'need a podfile')
+      @sandbox  = sandbox || raise(ArgumentError, 'Missing required argument `sandbox`')
+      @podfile  = podfile || raise(ArgumentError, 'Missing required argument `podfile`')
       @lockfile = lockfile
 
       @use_default_plugins = true

lib/cocoapods/resolver.rb

@@ -139,7 +139,7 @@ module Pod
           resolver_specs_by_target[target] = vertices.
             map do |vertex|
               payload = vertex.payload
-              test_only = vertex.recursive_predecessors.all? { |v| !v.root? || v.payload.test_specification? } && (!vertex.root? || payload.test_specification?)
+              test_only = (!vertex.root? || payload.test_specification?) && vertex.recursive_predecessors.all? { |v| !v.root? || v.payload.test_specification? }
               spec_source = payload.respond_to?(:spec_source) && payload.spec_source
               ResolverSpecification.new(payload, test_only, spec_source)
             end.
@@ -535,7 +535,9 @@ module Pod
     #
     # @return [Bool]
     def spec_is_platform_compatible?(dependency_graph, dependency, spec)
-      return true if locked_dependencies.vertex_named(spec.name) # HACK: this probably isn't safe?
+      # This is safe since a pod will only be in locked dependencies if we're
+      # using the same exact version
+      return true if locked_dependencies.vertex_named(spec.name)
 
       vertex = dependency_graph.vertex_named(dependency.name)
       predecessors = vertex.recursive_predecessors.select(&:root?)