Refactor and add some specs

Gemfile.lock

@@ -28,6 +28,8 @@ GEM
       i18n (~> 0.7)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
+    addressable (2.5.2)
+      public_suffix (>= 2.0.2, < 4.0)
     aws-partitions (1.71.0)
     aws-sdk-core (3.17.1)
       aws-partitions (~> 1.0)
@@ -39,9 +41,12 @@ GEM
     aws-sigv4 (1.0.2)
     builder (3.2.3)
     concurrent-ruby (1.0.5)
+    crack (0.4.3)
+      safe_yaml (~> 1.0.0)
     crass (1.0.3)
     diff-lcs (1.3)
     erubi (1.7.1)
+    hashdiff (0.3.7)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
     jmespath (1.3.1)
@@ -53,6 +58,7 @@ GEM
     minitest (5.11.3)
     nokogiri (1.8.2)
       mini_portile2 (~> 2.3.0)
+    public_suffix (3.0.2)
     rack (2.0.4)
     rack-test (0.8.3)
       rack (>= 1.0, < 3)
@@ -81,10 +87,15 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.7.0)
     rspec-support (3.7.1)
+    safe_yaml (1.0.4)
     thor (0.20.0)
     thread_safe (0.3.6)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
+    webmock (3.3.0)
+      addressable (>= 2.3.6)
+      crack (>= 0.3.2)
+      hashdiff
 
 PLATFORMS
   ruby
@@ -95,6 +106,7 @@ DEPENDENCIES
   psenv-rails!
   rake (~> 10.0)
   rspec (~> 3.0)
+  webmock (~> 3.3)
 
 BUNDLED WITH
    1.16.1

lib/psenv.rb

@@ -1,3 +1,5 @@
+require "psenv/environment"
+require "psenv/retriever"
 require "psenv/version"
 
 require "aws-sdk-ssm"
@@ -5,19 +7,17 @@ require "aws-sdk-ssm"
 module Psenv
   module_function
 
-  def load
-    if ENV["PARAMETER_STORE_PATH"] != nil
-      ssm = Aws::SSM::Client.new
+  def load(*paths)
+    paths.unshift(ENV["PARAMETER_STORE_PATH"]) if ENV["PARAMETER_STORE_PATH"]
+    Environment.create(*paths.map { |path| retrieve_variables(path) }).apply
+  end
 
-      ssm.
-        get_parameters_by_path(
-          path: ENV["PARAMETER_STORE_PATH"],
-          with_decryption: true,
-        ).
-        parameters.
-        each do |param|
-          ENV.store(param.name.split("/").last, param.value)
-        end
-    end
+  def overload(*paths)
+    paths.unshift(ENV["PARAMETER_STORE_PATH"]) if ENV["PARAMETER_STORE_PATH"]
+    Environment.create(*paths.map { |path| retrieve_variables(path) }).apply!
+  end
+
+  def retrieve_variables(path)
+    Retriever.new(path).call
   end
 end

lib/psenv/environment.rb

@@ -0,0 +1,15 @@
+module Psenv
+  class Environment < Hash
+    def apply
+      each { |k, v| ENV.store(k, v) unless ENV.has_key?(k) }
+    end
+
+    def apply!
+      each { |k, v| ENV.store(k, v) }
+    end
+
+    def self.create(*variables)
+      Environment[variables.reverse.reduce({}, :merge)]
+    end
+  end
+end

lib/psenv/retriever.rb

@@ -0,0 +1,48 @@
+require "aws-sdk-ssm"
+
+module Psenv
+  class RetrieveError < StandardError; end
+
+  class Parameter
+    attr_reader :name, :value
+
+    def initialize(parameter)
+      @name = parameter[:name].split("/").last
+      @value = parameter[:value]
+      @type = parameter[:type]
+      @version = parameter[:version]
+    end
+  end
+
+  class Retriever
+    def initialize(path)
+      @path = path
+    end
+
+    def call
+      Hash[
+        parameters.
+          map { |parameter| Parameter.new(parameter) }.
+          map { |parameter| [parameter.name, parameter.value] }
+      ]
+    end
+
+    def self.call(path)
+      new(path).call
+    end
+
+    private
+
+    def ssm
+      @ssm ||= Aws::SSM::Client.new
+    end
+
+    def parameters
+      ssm.
+        get_parameters_by_path(path: @path, with_decryption: true).
+        parameters
+    rescue StandardError => error
+      raise RetrieveError, error
+    end
+  end
+end

psenv.gemspec

@@ -23,6 +23,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 1.16"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "rspec", "~> 3.0"
+  spec.add_development_dependency "webmock", "~> 3.3"
 
   spec.add_dependency "aws-sdk-ssm", "~> 1"
 end

spec/psenv_rails_spec.rb

@@ -0,0 +1,24 @@
+require "spec_helper"
+require "rails"
+require "psenv-rails"
+
+RSpec.describe Psenv::Railtie do
+  before(:each) do
+    Rails.env = "test"
+    Rails.application = double(:application)
+  end
+
+  context "before_configuration" do
+    it "calls #load" do
+      expect(Psenv::Railtie.instance).to receive(:load)
+      ActiveSupport.run_load_hooks(:before_configuration)
+    end
+  end
+
+  context ".load" do
+    it "calls Psenv.load" do
+      expect(Psenv).to receive(:load)
+      Psenv::Railtie.load
+    end
+  end
+end

spec/psenv_spec.rb

@@ -1,7 +1,114 @@
+require "spec_helper"
+
 RSpec.describe Psenv do
+  let(:env_path) { "/env/" }
+  let(:arg_paths) { ["/arg1/", "/arg2"] }
+  let(:env_variables) { { TEST: "env", ANOTHER: "env" } }
+  let(:arg_variables) do
+    [{ ONE: "arg1", TWO: "arg1" }, { TWO: "arg2", THREE: "arg2" }]
+  end
+  let(:retriever1) { double(:retriever) }
+  let(:retriever2) { double(:retriever) }
+  let(:retriever3) { double(:retriever) }
+  let(:environment) { double(:environment) }
+
+  before(:each) do
+    allow(Psenv::Retriever).to receive(:new).with(env_path) { retriever1 }
+    allow(Psenv::Retriever).to receive(:new).with(arg_paths[0]) { retriever2 }
+    allow(Psenv::Retriever).to receive(:new).with(arg_paths[1]) { retriever3 }
+    allow(retriever1).to receive(:call) { env_variables }
+    allow(retriever2).to receive(:call) { arg_variables[0] }
+    allow(retriever3).to receive(:call) { arg_variables[1] }
+    allow(Psenv::Environment).to receive(:create) { environment }
+    allow(environment).to receive(:apply)
+    allow(environment).to receive(:apply!)
+
+    ENV.store("PARAMETER_STORE_PATH", nil)
+  end
+
   it "has a version number" do
     expect(Psenv::VERSION).not_to be nil
   end
 
-  it "tests something useful"
+  context ".load" do
+    context "when PARAMETER_STORE_PATH is set" do
+      before(:each) do
+        ENV.store("PARAMETER_STORE_PATH", env_path)
+        Psenv.load
+      end
+
+      it "retrieves the correct path" do
+        expect(Psenv::Retriever).to have_received(:new).with(env_path)
+      end
+
+      it "creates the environment with the correct variables" do
+        expect(Psenv::Environment).
+          to have_received(:create).with(env_variables)
+      end
+
+      it "applies the environment" do
+        expect(environment).to have_received(:apply)
+      end
+    end
+
+    context "when paths are passed in" do
+      before(:each) { Psenv.load(*arg_paths) }
+
+      it "retrieves the correct paths" do
+        arg_paths.each do |path|
+          expect(Psenv::Retriever).to have_received(:new).with(path)
+        end
+      end
+
+      it "creates the environment with the correct variables" do
+        expect(Psenv::Environment).
+          to have_received(:create).with(*arg_variables)
+      end
+
+      it "apples the environment" do
+        expect(environment).to have_received(:apply)
+      end
+    end
+  end
+
+  context ".overload" do
+    context "when PARAMETER_STORE_PATH is set" do
+      before(:each) do
+        ENV.store("PARAMETER_STORE_PATH", env_path)
+        Psenv.overload
+      end
+
+      it "retrieves the correct path" do
+        expect(Psenv::Retriever).to have_received(:new).with(env_path)
+      end
+
+      it "creates the environment with the correct variables" do
+        expect(Psenv::Environment).
+          to have_received(:create).with(env_variables)
+      end
+
+      it "applies the environment" do
+        expect(environment).to have_received(:apply!)
+      end
+    end
+
+    context "when paths are passed in" do
+      before(:each) { Psenv.overload(*arg_paths) }
+
+      it "retrieves the correct paths" do
+        arg_paths.each do |path|
+          expect(Psenv::Retriever).to have_received(:new).with(path)
+        end
+      end
+
+      it "creates the environment with the correct variables" do
+        expect(Psenv::Environment).
+          to have_received(:create).with(*arg_variables)
+      end
+
+      it "apples the environment" do
+        expect(environment).to have_received(:apply!)
+      end
+    end
+  end
 end

spec/spec_helper.rb

@@ -1,6 +1,9 @@
 require "bundler/setup"
+require 'webmock/rspec'
 require "psenv"
 
+WebMock.disable_net_connect!(allow_localhost: true)
+
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
   config.example_status_persistence_file_path = ".rspec_status"