Add specs for value types

spec/spectator/wrapper_spec.cr

@@ -0,0 +1,18 @@
+require "../spec_helper"
+
+Spectator.describe Spectator::Wrapper do
+  it "stores a value" do
+    wrapper = described_class.new(42)
+    expect(wrapper.get(Int32)).to eq(42)
+  end
+
+  it "retrieves a value using the block trick" do
+    wrapper = described_class.new(Int32)
+    expect(wrapper.get { Int32 }).to eq(Int32)
+  end
+
+  it "raises on invalid cast" do
+    wrapper = described_class.new(42)
+    expect { wrapper.get(String) }.to raise_error(TypeCastError)
+  end
+end