Add unit tests for PluginInstaller

spec/lib/capistrano/configuration/plugin_installer_spec.rb

@@ -0,0 +1,98 @@
+require "spec_helper"
+require "capistrano/plugin"
+require "capistrano/scm/plugin"
+
+module Capistrano
+  class Configuration
+    class ExamplePlugin < Capistrano::Plugin
+      def set_defaults
+        set_if_empty :example_variable, "foo"
+      end
+
+      def define_tasks
+        task :example
+        task :example_prerequisite
+      end
+
+      def register_hooks
+        before :example, :example_prerequisite
+      end
+    end
+
+    class ExampleSCMPlugin < Capistrano::SCM::Plugin
+    end
+
+    describe PluginInstaller do
+      include Capistrano::DSL
+
+      let(:installer) { PluginInstaller.new }
+      let(:options) { {} }
+      let(:plugin) { ExamplePlugin.new }
+
+      before do
+        installer.install(plugin, **options)
+      end
+
+      after do
+        Rake::Task.clear
+        Capistrano::Configuration.reset!
+      end
+
+      context "installing plugin" do
+        it "defines tasks" do
+          expect(Rake::Task[:example]).to_not be_nil
+          expect(Rake::Task[:example_prerequisite]).to_not be_nil
+        end
+
+        it "registers hooks" do
+          task = Rake::Task[:example]
+          expect(task.prerequisites).to eq([:example_prerequisite])
+        end
+
+        it "sets defaults when load:defaults is invoked" do
+          expect(fetch(:example_variable)).to be_nil
+          invoke "load:defaults"
+          expect(fetch(:example_variable)).to eq("foo")
+        end
+
+        it "doesn't say an SCM is installed" do
+          expect(installer.scm_installed?).to be_falsey
+        end
+      end
+
+      context "installing plugin class" do
+        let(:plugin) { ExamplePlugin }
+
+        it "defines tasks" do
+          expect(Rake::Task[:example]).to_not be_nil
+          expect(Rake::Task[:example_prerequisite]).to_not be_nil
+        end
+      end
+
+      context "installing plugin without hooks" do
+        let(:options) { { load_hooks: false } }
+
+        it "doesn't register hooks" do
+          task = Rake::Task[:example]
+          expect(task.prerequisites).to be_empty
+        end
+      end
+
+      context "installing plugin and loading immediately" do
+        let(:options) { { load_immediately: true } }
+
+        it "sets defaults immediately" do
+          expect(fetch(:example_variable)).to eq("foo")
+        end
+      end
+
+      context "installing an SCM plugin" do
+        let(:plugin) { ExampleSCMPlugin }
+
+        it "says an SCM is installed" do
+          expect(installer.scm_installed?).to be_truthy
+        end
+      end
+    end
+  end
+end