Fix schema diffing

* When the prior schema didn't have "stats", we would blow up
* Because the prior schema is from a JSON file and the new one is
generated programmatically, we could enter scenarios incorrectly
comparing string values to symbol values. Always parse as JSON to avoid
this.

Author: Lee Richmond

lib/graphiti/schema_diff.rb

@@ -1,8 +1,8 @@
 module Graphiti
   class SchemaDiff
     def initialize(old, new)
-      @old = old.deep_symbolize_keys
-      @new = new.deep_symbolize_keys
+      @old = JSON.parse(old.to_json).deep_symbolize_keys
+      @new = JSON.parse(new.to_json).deep_symbolize_keys
       @errors = []
     end
 
@@ -135,12 +135,12 @@ def compare_sorts(old_resource, new_resource)
         end
 
         if new_sort[:only] && !old_sort[:only]
-          @errors << "#{old_resource[:name]}: sort #{name.inspect} now limited to only #{new_sort[:only].inspect}."
+          @errors << "#{old_resource[:name]}: sort #{name.inspect} now limited to only #{new_sort[:only].to_sym.inspect}."
         end
 
         if new_sort[:only] && old_sort[:only]
           if new_sort[:only] != old_sort[:only]
-            @errors << "#{old_resource[:name]}: sort #{name.inspect} was limited to only #{old_sort[:only].inspect}, now limited to only #{new_sort[:only].inspect}."
+            @errors << "#{old_resource[:name]}: sort #{name.inspect} was limited to only #{old_sort[:only].to_sym.inspect}, now limited to only #{new_sort[:only].to_sym.inspect}."
           end
         end
       end
@@ -212,28 +212,30 @@ def compare_filter_group(old_resource, new_resource)
           new_names = new_resource[:filter_group][:names]
           old_names = old_resource[:filter_group][:names]
           diff = new_names - old_names
-          if !diff.empty? && new_resource[:filter_group][:required] == :all
-            @errors << "#{old_resource[:name]}: all required filter group #{old_names.inspect} added #{"member".pluralize(diff.length)} #{diff.inspect}."
+          if !diff.empty? && new_resource[:filter_group][:required] == "all"
+            @errors << "#{old_resource[:name]}: all required filter group #{old_names.map(&:to_sym).inspect} added #{"member".pluralize(diff.length)} #{diff.map(&:to_sym).inspect}."
           end
 
           old_required = old_resource[:filter_group][:required]
           new_required = new_resource[:filter_group][:required]
-          if old_required == :any && new_required == :all
-            @errors << "#{old_resource[:name]}: filter group #{old_names.inspect} moved from required: :any to required: :all"
+          if old_required == "any" && new_required == "all"
+            @errors << "#{old_resource[:name]}: filter group #{old_names.map(&:to_sym).inspect} moved from required: :any to required: :all"
           end
         else
-          @errors << "#{old_resource[:name]}: filter group #{new_resource[:filter_group][:names].inspect} was added."
+          @errors << "#{old_resource[:name]}: filter group #{new_resource[:filter_group][:names].map(&:to_sym).inspect} was added."
         end
       end
     end
 
     def compare_stats(old_resource, new_resource)
+      return unless old_resource.key?(:stats)
+
       old_resource[:stats].each_pair do |name, old_calculations|
         new_calculations = new_resource[:stats][name]
         if new_calculations
           old_calculations.each do |calc|
             unless new_calculations.include?(calc)
-              @errors << "#{old_resource[:name]}: calculation #{calc.inspect} was removed from stat #{name.inspect}."
+              @errors << "#{old_resource[:name]}: calculation #{calc.to_sym.inspect} was removed from stat #{name.inspect}."
             end
           end
         else

lib/graphiti/version.rb

@@ -1,3 +1,3 @@
 module Graphiti
-  VERSION = "1.2.36"
+  VERSION = "1.2.37"
 end

spec/schema_diff_spec.rb

@@ -891,6 +891,18 @@ def self.name
       end
     end
 
+    context "when the original schema does not have stats" do
+      before do
+        a[:resources].each { |r| r.delete(:stats) }
+      end
+
+      it "does not blow up" do
+        expect {
+          expect(diff).to eq([])
+        }.to_not raise_error
+      end
+    end
+
     context "when a stat is added" do
       before do
         resource_a.stat age: [:sum]
@@ -1193,7 +1205,7 @@ def self.name
 
         it "returns error" do
           expect(diff).to eq([
-            'Endpoint "/schema_diff/employees" had incompatible sideload allowlist. Was [{:positions=>:department}, :same], now [:positions, :same].'
+            'Endpoint "/schema_diff/employees" had incompatible sideload allowlist. Was [{:positions=>"department"}, "same"], now ["positions", "same"].'
           ])
         end
       end