Ensure stubs defined with allow syntax are cleared

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Fixed
 - Clear stubs defined with `expect().to receive()` syntax after test finishes to prevent leakage between tests.
+- Ensure stubs defined with `allow().to receive()` syntax are cleared after test finishes when used inside a test (another leakage).
 
 ### Removed
 - Removed support for stubbing undefined (untyped) methods in lazy doubles. Avoids possible segfault.

spec/spectator/mocks/allow_spec.cr

@@ -9,5 +9,31 @@ Spectator.describe Spectator::Allow do
     it "applies a stub" do
       expect { alw.to(stub) }.to change { dbl.foo }.from(42).to(123)
     end
+
+    context "leak" do
+      class Thing
+        def foo
+          42
+        end
+      end
+
+      mock Thing
+
+      getter(thing : Thing) { mock(Thing) }
+
+      # Workaround type restrictions requiring a constant.
+      def fake
+        class_mock(Thing).cast(thing)
+      end
+
+      specify do
+        expect { allow(fake).to(stub) }.to change { fake.foo }.from(42).to(123)
+      end
+
+      # This example must be run after the previous (random order may break this).
+      it "clears the stub after the example completes" do
+        expect { fake.foo }.to eq(42)
+      end
+    end
   end
 end

src/spectator/mocks/allow.cr

@@ -1,3 +1,4 @@
+require "../harness"
 require "./stub"
 require "./stubbable"
 require "./stubbed_type"
@@ -21,6 +22,7 @@ module Spectator
     # Applies a stub to the targeted stubbable object.
     def to(stub : Stub) : Nil
       @target._spectator_define_stub(stub)
+      Harness.current?.try &.cleanup { @target._spectator_remove_stub(stub) }
     end
   end
 end