Allow projection from one stream only

Author: lukaszreszke

ruby_event_store/lib/ruby_event_store/projection.rb

@@ -21,12 +21,10 @@ def on(*event_klasses, &block)
       self
     end
 
-    def call(*scopes)
+    def call(scope)
       return initial_state if handled_events.empty?
 
-      scopes.reduce(initial_state) do |state, scope|
-        scope.of_types(handled_events).reduce(state, &method(:transition))
-      end
+      scope.of_types(handled_events).reduce(initial_state, &method(:transition))
     end
 
     private

ruby_event_store/spec/projection_spec.rb

@@ -32,20 +32,6 @@ module RubyEventStore
       expect(account_balance).to eq(25)
     end
 
-    specify "reduce events from many streams" do
-      event_store.append(MoneyDeposited.new(data: { amount: 10 }), stream_name: "Customer$1")
-      event_store.append(MoneyDeposited.new(data: { amount: 20 }), stream_name: "Customer$2")
-      event_store.append(MoneyWithdrawn.new(data: { amount: 5 }), stream_name: "Customer$3")
-
-      account_balance =
-        Projection
-          .new(0)
-          .on(MoneyDeposited) { |state, event| state += event.data[:amount] }
-          .on(MoneyWithdrawn) { |state, event| state -= event.data[:amount] }
-          .call(event_store.read.stream("Customer$1"), event_store.read.stream("Customer$3"))
-      expect(account_balance).to eq(5)
-    end
-
     specify "take events from all streams" do
       event_store.append(MoneyDeposited.new(data: { amount: 1 }), stream_name: "Customer$1")
       event_store.append(MoneyDeposited.new(data: { amount: 1 }), stream_name: "Customer$2")