Implement Validators.get

lib/kangaru/validators.rb

@@ -0,0 +1,29 @@
+module Kangaru
+  module Validators
+    using Patches::Inflections
+
+    def self.get(name)
+      class_name = name.to_s.to_class_name(suffix: :validator)
+
+      from_kangaru(class_name) || from_application(class_name) ||
+        raise("#{class_name} is not defined")
+    end
+
+    def self.from_kangaru(class_name)
+      return unless const_defined?(class_name)
+
+      const_get(class_name)
+    end
+
+    def self.from_application(class_name)
+      namespace = Kangaru.application&.const_get(:Validators)
+
+      return unless namespace&.const_defined?(class_name)
+
+      namespace.const_get(class_name)
+    end
+
+    private_class_method :from_kangaru
+    private_class_method :from_application
+  end
+end

sig/kangaru/validators.rbs

@@ -0,0 +1,11 @@
+module Kangaru
+  module Validators
+    def self.get: (String | Symbol) -> singleton(Validator)
+
+    private
+
+    def self.from_kangaru: (String | Symbol) -> singleton(Validator)?
+
+    def self.from_application: (String | Symbol) -> singleton(Validator)?
+  end
+end

spec/kangaru/validators_spec.rb

@@ -0,0 +1,92 @@
+RSpec.describe Kangaru::Validators do
+  describe ".get", :stub_application do
+    subject(:validator) { described_class.get(name) }
+
+    let(:validator_class) do
+      Class.new(Kangaru::Validator)
+    end
+
+    let(:name) { "example" }
+
+    shared_examples :raises_error do
+      it "raises an error" do
+        expect { validator }.to raise_error(
+          "ExampleValidator is not defined"
+        )
+      end
+    end
+
+    shared_examples :returns_validator_class do
+      it "does not raise any errors" do
+        expect { validator }.not_to raise_error
+      end
+
+      it "returns the validator class" do
+        expect(validator).to eq(validator_class)
+      end
+    end
+
+    context "when application is not set" do
+      let(:application) { nil }
+
+      context "and validator is not defined by Kangaru" do
+        include_examples :raises_error
+      end
+
+      context "and validator is defined by Kangaru" do
+        before do
+          stub_const "#{described_class}::ExampleValidator", validator_class
+        end
+
+        include_examples :returns_validator_class
+      end
+    end
+
+    context "when application is set" do
+      let(:application) { instance_double(Kangaru::Application, namespace:) }
+
+      let(:validators_namespace) { nil }
+
+      before do
+        allow(application)
+          .to receive(:const_get)
+          .with(:Validators)
+          .and_return(validators_namespace)
+      end
+
+      context "and validator is not defined by Kangaru" do
+        context "and validators namespace is not defined by application" do
+          let(:validators_namespace) { nil }
+
+          include_examples :raises_error
+        end
+
+        context "and validators namespace is defined by application" do
+          let(:validators_namespace) { Module.new }
+
+          before do
+            allow(application)
+              .to receive(:const_get)
+              .with(:Validators)
+              .and_return(validators_namespace)
+
+            stub_const "#{namespace}::Validators", validators_namespace
+          end
+
+          context "and validator class is not defined" do
+            include_examples :raises_error
+          end
+
+          context "and validator class is defined" do
+            before do
+              stub_const "#{validators_namespace}::ExampleValidator",
+                         validator_class
+            end
+
+            include_examples :returns_validator_class
+          end
+        end
+      end
+    end
+  end
+end