Document receive(:msg).with(satisfy{|arg| ... })

README.md

@@ -278,6 +278,8 @@ expect(double).to receive(:msg).with(1, duck_type(:abs, :div), "b") #2nd argumen
 expect(double).to receive(:msg).with(hash_including(:a => 5)) # first arg is a hash with a: 5 as one of the key-values
 expect(double).to receive(:msg).with(array_including(5)) # first arg is an array with 5 as one of the key-values
 expect(double).to receive(:msg).with(hash_excluding(:a => 5)) # first arg is a hash without a: 5 as one of the key-values
+expect(double).to receive(:msg).with(start_with('a')) # any matcher, custom or from rspec-expectations
+expect(double).to receive(:msg).with(satisfy { |data| data.dig(:a, :b, :c) == 5 }) # assert anything you want
 ```
 
 ## Receive Counts

features/setting_constraints/matching_arguments.feature

@@ -133,6 +133,37 @@ Feature: Matching arguments
       | expected: (a collection containing exactly 1 and 2)           |
       | got: ([1, 3])                                                 |
 
+  @ripper
+  Scenario: Using satisfy for complex custom expecations
+    Given a file named "rspec_satisfy_spec.rb" with:
+      """ruby
+      RSpec.describe "Using satisfy for complex custom expecations" do
+        let(:dbl) { double }
+
+        def a_b_c_equals_5
+          satisfy { |data| data[:a][:b][:c] == 5 }
+        end
+
+        it "passes when the expectation is true" do
+          expect(dbl).to receive(:foo).with(a_b_c_equals_5)
+          dbl.foo({ :a => { :b => { :c => 5 } } })
+        end
+
+        it "fails when the expectation is false" do
+          expect(dbl).to receive(:foo).with(a_b_c_equals_5)
+          dbl.foo({ :a => { :b => { :c => 3 } } })
+        end
+      end
+      """
+    When I run `rspec rspec_satisfy_spec.rb`
+    Then it should fail with the following output:
+      | 2 examples, 1 failure                                         |
+      |                                                               |
+      | Failure/Error: dbl.foo({ :a => { :b => { :c => 3 } } })       |
+      | #<Double (anonymous)> received :foo with unexpected arguments |
+      | expected: (satisfy expression `data[:a][:b][:c] == 5`)        |
+      |      got: ({:a=>{:b=>{:c=>3}}})                               |
+
   Scenario: Using a custom matcher
     Given a file named "custom_matcher_spec.rb" with:
       """ruby

features/support/env.rb

@@ -21,6 +21,17 @@
   end
 end
 
+Before('@ripper') do |scenario|
+  unless RSpec::Support::RubyFeatures.ripper_supported?
+    warn "Skipping scenario due to lack of Ripper support"
+    if Cucumber::VERSION.to_f >= 3.0
+      skip_this_scenario
+    else
+      scenario.skip_invoke!
+    end
+  end
+end
+
 Before('@kw-arguments') do |scenario|
   unless RSpec::Support::RubyFeatures.kw_args_supported?
     warn "Skipping scenario due to lack of keyword argument support"