Move instruction->validator mapping to instruction class

lib/nandi/instructions/add_column.rb

@@ -19,6 +19,10 @@ def procedure
       def lock
         Nandi::Migration::LockWeights::ACCESS_EXCLUSIVE
       end
+
+      def validator
+        Validation::AddColumnValidator
+      end
     end
   end
 end

lib/nandi/instructions/add_index.rb

@@ -32,6 +32,10 @@ def lock
         Nandi::Migration::LockWeights::SHARE
       end
 
+      def validator
+        Validation::AddIndexValidator
+      end
+
       attr_reader :table, :fields
 
       private

lib/nandi/instructions/add_reference.rb

@@ -19,6 +19,10 @@ def procedure
       def lock
         Nandi::Migration::LockWeights::ACCESS_EXCLUSIVE
       end
+
+      def validator
+        Validation::AddReferenceValidator
+      end
     end
   end
 end

lib/nandi/instructions/remove_index.rb

@@ -24,6 +24,10 @@ def lock
         Nandi::Migration::LockWeights::SHARE
       end
 
+      def validator
+        Validation::RemoveIndexValidator
+      end
+
       attr_reader :table
 
       private

lib/nandi/validation/each_validator.rb

@@ -16,18 +16,9 @@ def initialize(instruction)
       end
 
       def call
-        case instruction.procedure
-        when :add_index
-          AddIndexValidator.call(instruction)
-        when :remove_index
-          RemoveIndexValidator.call(instruction)
-        when :add_column
-          AddColumnValidator.call(instruction)
-        when :add_reference
-          AddReferenceValidator.call(instruction)
-        else
-          success
-        end
+        return success unless instruction.respond_to?(:validator)
+
+        instruction.validator.call(instruction)
       end
 
       attr_reader :instruction

lib/nandi/validation/failure_helpers.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "dry/monads/result"
+require "dry/monads"
 
 module Nandi
   module Validation

spec/nandi/validation/each_validator_spec.rb

@@ -11,11 +11,7 @@
 
   describe "#call" do
     context "when the given instruction is to remove an index" do
-      let(:instruction) { instance_double(Nandi::Instructions::RemoveIndex) }
-
-      before do
-        allow(instruction).to receive(:procedure).and_return(:remove_index)
-      end
+      let(:instruction) { Nandi::Instructions::RemoveIndex.new(table: :payments, field: :foo) }
 
       it "calls RemoveIndexValidator" do
         expect(Nandi::Validation::RemoveIndexValidator).to receive(:call).
@@ -26,11 +22,7 @@
     end
 
     context "when the given instruction is to add a column" do
-      let(:instruction) { instance_double(Nandi::Instructions::AddColumn) }
-
-      before do
-        allow(instruction).to receive(:procedure).and_return(:add_column)
-      end
+      let(:instruction) { Nandi::Instructions::AddColumn.new(table: :payments, name: :foo, type: :text) }
 
       it "calls AddColumnValidator" do
         expect(Nandi::Validation::AddColumnValidator).to receive(:call).with(instruction)
@@ -40,11 +32,7 @@
     end
 
     context "when the given instruction is to add a reference" do
-      let(:instruction) { instance_double(Nandi::Instructions::AddReference) }
-
-      before do
-        allow(instruction).to receive(:procedure).and_return(:add_reference)
-      end
+      let(:instruction) { Nandi::Instructions::AddReference.new(table: :payments, ref_name: :user) }
 
       it "calls AddReferenceValidator" do
         expect(Nandi::Validation::AddReferenceValidator).to receive(:call).
@@ -55,11 +43,7 @@
     end
 
     context "when the given instruction is to add an index" do
-      let(:instruction) { instance_double(Nandi::Instructions::AddIndex) }
-
-      before do
-        allow(instruction).to receive(:procedure).and_return(:add_index)
-      end
+      let(:instruction) { Nandi::Instructions::AddIndex.new(table: :payments, fields: [:foo]) }
 
       it "calls AddIndexValidator" do
         expect(Nandi::Validation::AddIndexValidator).to receive(:call).
@@ -70,11 +54,7 @@
     end
 
     context "when the given instruction isn't explicitly validated" do
-      let(:instruction) { instance_double(Nandi::Instructions::AddForeignKey) }
-
-      before do
-        allow(instruction).to receive(:procedure).and_return(:add_foreign_key)
-      end
+      let(:instruction) { Nandi::Instructions::AddForeignKey.new(table: :payments, target: :users) }
 
       it "returns successful" do
         expect(call).to eq(Dry::Monads::Result::Success.new(nil))