Add deposit concept

spec/deposit_spec.cr

@@ -0,0 +1,38 @@
+require "./spec_helper"
+
+module Game::Test
+  describe Deposit do
+    it "should be created fulfilled" do
+      dep = Deposit.new(Resources::Type::Crystals, 100)
+      dep.cap.should eq 100
+      dep.cur.should eq 100
+    end
+
+    it "can be created partially filled" do
+      dep = Deposit.new(Resources::Type::Crystals, 100, 20)
+      dep.cap.should eq 100
+      dep.cur.should eq 20
+    end
+
+    it "should be decreased with span" do
+      dep = Deposit.new(Resources::Type::Crystals, 100)
+      dep.dec Deposit::Span.new(Resources::Type::Crystals, 20)
+      dep.cap.should eq 100
+      dep.cur.should eq 80
+    end
+
+    it "should not be increased above capacity" do
+      dep = Deposit.new(Resources::Type::Crystals, 100, 20)
+      dep.inc Deposit::Span.new(Resources::Type::Crystals, 100)
+      dep.cap.should eq 100
+      dep.cur.should eq 100
+    end
+
+    it "should not be decreased below zero" do
+      dep = Deposit.new(Resources::Type::Crystals, 100)
+      dep.dec Deposit::Span.new(Resources::Type::Crystals, 120)
+      dep.cap.should eq 100
+      dep.cur.should eq 0
+    end
+  end
+end