Adds better nil value handling for theme

lib/protos/theme.rb

@@ -40,6 +40,8 @@ def key?(key)
     end
 
     def add(key, value)
+      return if value.nil?
+
       @theme[key].add(value)
     end
 
@@ -49,6 +51,8 @@ def remove(key, value)
     end
 
     def set(key, value)
+      return if value.nil?
+
       @theme[key].clear.add(value)
     end
 

spec/protos/attributes_spec.rb

@@ -15,6 +15,10 @@
       attrs = described_class.new(foo: "bar")
       expect(attrs[:foo]).to eq("bar")
     end
+
+    it "handles non-existent attributes" do
+      expect(subject[:foo]).to be_nil
+    end
   end
 
   describe "#merge" do

spec/protos/theme_spec.rb

@@ -52,20 +52,26 @@
 
       expect(subject[:foo]).to eq("foo bar")
     end
+
+    it "handles nil values" do
+      subject.add(:foo, nil)
+
+      expect(subject[:foo]).to be(nil)
+    end
   end
 
   describe "#remove" do
     it "removes a class from the theme" do
       theme = described_class.new(foo: "bar")
       theme.remove(:foo, "bar")
 
-      expect(theme[:foo]).to eq(nil)
+      expect(theme[:foo]).to be(nil)
     end
 
     it "handles removing a non existing key" do
       subject.remove(:foo, "bar")
 
-      expect(subject[:foo]).to eq(nil)
+      expect(subject[:foo]).to be(nil)
     end
   end
 
@@ -76,6 +82,12 @@
 
       expect(subject[:foo]).to eq("baz")
     end
+
+    it "handles nil values" do
+      subject.set(:foo, nil)
+
+      expect(subject[:foo]).to be_nil
+    end
   end
 
   describe "#[]" do