Prevent duplicate invocation of the error callback when guarding an i…

…nstance method

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 0.9.2
+
+### Bug fixes
+
+- Prevent duplicate invocation of the error callback when guarding an instance
+  method.
+
 ## 0.9.1
 
 ### Bug fixes

Gemfile.lock

@@ -1,19 +1,19 @@
 PATH
   remote: .
   specs:
-    stimpack (0.9.1)
+    stimpack (0.9.2)
       activesupport (>= 6.1)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (7.0.2.2)
+    activesupport (7.0.3)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
       tzinfo (~> 2.0)
     ast (2.4.2)
-    concurrent-ruby (1.1.9)
+    concurrent-ruby (1.1.10)
     diff-lcs (1.4.4)
     i18n (1.10.0)
       concurrent-ruby (~> 1.0)

lib/stimpack/result_monad/guard_clause.rb

@@ -29,7 +29,11 @@ module GuardCatcher
         def call
           super
         rescue GuardFailed => e
-          run_callback(:error)
+          # Avoid running the error callback in the case where it was already
+          # called by using `#error` in an instance method that is guarded
+          # against in the `#call` method.
+          #
+          run_callback(:error) unless e.result.klass == self.class
 
           e.result
         end

lib/stimpack/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Stimpack
-  VERSION = "0.9.1"
+  VERSION = "0.9.2"
 end

spec/stimpack/result_monad/guard_clause_spec.rb

@@ -5,14 +5,21 @@
 RSpec.describe Stimpack::ResultMonad::GuardClause do
   subject(:service) { klass }
 
-  let(:instance) { service.new }
+  let(:instance) { service.new(private_error: private_error) }
+  let(:private_error) { false }
 
   let(:klass) do
     Class.new do
       include Stimpack::ResultMonad
 
       result :foo
 
+      def initialize(private_error: false)
+        @private_error = private_error
+      end
+
+      attr_reader :private_error
+
       def success_result(**options)
         success(**options)
       end
@@ -27,9 +34,12 @@ def self.to_s
 
       def call
         guard :foo
+
         bar_result = guard { bar }
         baz_result = guard { baz }
 
+        guard { qux } if private_error
+
         success(foo: bar_result + baz_result)
       rescue StandardError
         error(errors: "Something went wrong, but not a guard fail.")
@@ -48,13 +58,18 @@ def bar
       def baz
         pass("Baz")
       end
+
+      def qux
+        error(errors: ["Same class error"])
+      end
     end
   end
 
   let(:inner_service_error) do
     double(
       Stimpack::ResultMonad::Result,
       failed?: true,
+      klass: "Foo",
       errors: ["Inner error"]
     )
   end
@@ -63,6 +78,7 @@ def baz
     double(
       Stimpack::ResultMonad::Result,
       failed?: false,
+      klass: "Foo",
       unwrap!: "Foo",
       errors: nil
     )
@@ -121,15 +137,33 @@ def baz
   end
 
   describe ".before_error" do
-    before do
-      allow(instance).to receive(:inspect)
-      allow(instance).to receive(:foo).and_return(inner_service_error)
+    context "when inner service fails" do
+      before do
+        allow(instance).to receive(:inspect)
+        allow(instance).to receive(:foo).and_return(inner_service_error)
 
-      service.before_error { inspect }
+        service.before_error { inspect }
+
+        instance.()
+      end
 
-      instance.()
+      it { expect(instance).to have_received(:inspect).once }
     end
 
-    it { expect(instance).to have_received(:inspect).once }
+    context "when passing an error from an instance method" do
+      let(:private_error) { true }
+
+      before do
+        allow(instance).to receive(:inspect)
+        allow(instance).to receive(:foo).and_return(inner_service_success)
+        allow(instance).to receive(:bar).and_return(inner_service_success)
+
+        service.before_error { inspect }
+
+        instance.()
+      end
+
+      it { expect(instance).to have_received(:inspect).once }
+    end
   end
 end