Add specs for ids filter. Fix issue with string values

app/models/doi/graphql_query.rb

@@ -116,6 +116,10 @@ def must
 
     def filters
       options = @options
+
+      # turn ids into an array if provided as comma-separated string
+      options[:ids] = options[:ids].split(",") if options[:ids].is_a?(String)
+
       filter = []
       filter << { terms: { doi: options[:ids].map(&:upcase) } } if options[:ids].present?
       filter << { term: { "types.resourceTypeGeneral": options[:resource_type_id].underscore.camelize } } if options[:resource_type_id].present?

spec/models/doi/graphql_query_builder_spec.rb

@@ -57,4 +57,29 @@
       expect(described_class.new("foo/bar", {}).clean_query).to eq("foo\\/bar")
     end
   end
+
+  describe "filters"  do
+    it "is an empty array if not set" do
+      expect(described_class.new("", {}).filters).to eq([])
+      expect(described_class.new(nil, {}).filters).to eq([])
+    end
+
+    it "can filter for ids" do
+      expect(described_class.new("foo", { ids: ["bar"] }).filters).to eq([{ terms: { doi: ["BAR"] } }])
+    end
+
+    it "can filter for ids as single string" do
+      expect(described_class.new("foo", { ids: "bar" }).filters).to eq([{ terms: { doi: ["BAR"] } }])
+    end
+
+
+  end
+
+
+
+
+
+
+
+
 end