From 074a48a299494f810a724ad2698740425235b493 Mon Sep 17 00:00:00 2001
From: Piotr Solnica <piotr.solnica@gmail.com>
Date: Mon, 4 Mar 2019 12:03:25 +0100
Subject: [PATCH] Add Result#[]= and Result#key?

Closes #460
Closes #461
---
 lib/dry/validation/result.rb                  | 34 ++++++++++++-
 .../contract/evaluator/setting_values_spec.rb | 49 +++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 spec/integration/contract/evaluator/setting_values_spec.rb

diff --git a/lib/dry/validation/result.rb b/lib/dry/validation/result.rb
index 3abf6fae..82183bdc 100644
--- a/lib/dry/validation/result.rb
+++ b/lib/dry/validation/result.rb
@@ -79,7 +79,32 @@ def add_error(key, message)
       #
       # @api public
       def [](key)
-        values[key]
+        values.key?(key) && values[key] || storage.key?(key) && storage[key]
+      end
+
+      # Store value under specified key
+      #
+      # @param [Symbol] key
+      # @param [Object] value
+      #
+      # @return [Object]
+      #
+      # @api public
+      def []=(key, value)
+        raise ArgumentError, "Key +#{key}+ was already set" if key?(key)
+
+        storage[key] = value
+      end
+
+      # Check if a key was set
+      #
+      # @param [Symbol] key
+      #
+      # @return [Bool]
+      #
+      # @api public
+      def key?(key)
+        values.key?(key) || storage.key?(key)
       end
 
       # Coerce to a hash
@@ -103,6 +128,13 @@ def update(new_errors)
       def inspect
         "#<#{self.class}#{to_h.inspect} errors=#{errors.inspect}>"
       end
+
+      private
+
+      # @api private
+      def storage
+        @storage ||= EMPTY_HASH.dup
+      end
     end
   end
 end
diff --git a/spec/integration/contract/evaluator/setting_values_spec.rb b/spec/integration/contract/evaluator/setting_values_spec.rb
new file mode 100644
index 00000000..0c17d707
--- /dev/null
+++ b/spec/integration/contract/evaluator/setting_values_spec.rb
@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+RSpec.describe Dry::Validation::Evaluator, 'values writer' do
+  context 'when key does not exist' do
+    subject(:contract) do
+      Dry::Validation::Contract.build do
+        schema do
+          required(:email).filled(:string)
+          required(:user_id).filled(:integer)
+        end
+
+        rule(:user_id) do
+          if values[:user_id].equal?(312)
+            values[:user] = 'jane'
+          else
+            failure(:user, 'must be jane')
+          end
+        end
+
+        rule(:email) do
+          failure('is invalid') if values[:user] == 'jane' && values[:email] != 'jane@doe.org'
+        end
+      end
+    end
+
+    it 'stores new values between rule execution' do
+      expect(contract.(user_id: 3, email: 'john@doe.org').errors).to eql(user: ['must be jane'])
+      expect(contract.(user_id: 312, email: 'john@doe.org').errors).to eql(email: ['is invalid'])
+    end
+  end
+
+  context 'when key already exists' do
+    subject(:contract) do
+      Dry::Validation::Contract.build do
+        schema do
+          required(:email).filled(:string)
+        end
+
+        rule(:email) do
+          values[:email] = 'foo'
+        end
+      end
+    end
+
+    it 'raises error' do
+      expect { contract.(email: 'jane@doe.org') }.to raise_error(ArgumentError, /email/)
+    end
+  end
+end