Add partial rendering (#3)

jfharden · web-flow · commit 1ad5c4c95465 · 2018-02-02T23:23:47.000Z
* Add fixtures for partial rendering
* Update classes and exe to render partials.
* Bumped gem version, updated CHANGELOG and README.
* Added simple_partials example
* Fixes for some style points from code climate
diff --git a/.rubocop.yml b/.rubocop.yml
@@ -1,3 +1,6 @@
+AllCops:
+  TargetRubyVersion: 2.3
+
 Metrics/LineLength:
   Max: 119
   Exclude:
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 0.3.0 (2018-02-02)
+
+Features:
+
+ - Partials can now be rendered by calling `render 'path/to/partial.erb'` in the template.
+
 ## 0.2.0 (2018-01-29)
 
 Features:
diff --git a/Gemfile b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source "https://rubygems.org"
 
 gemspec
diff --git a/README.md b/README.md
@@ -23,6 +23,27 @@ provider](https://www.terraform.io/docs/providers/external/data_source.html) to
 terraform passes in the variables to render as a json blob to stdin as described above and expects a json blob
 back.
 
+## Rendering Partials
+
+Inside any template you can render a partial template by calling the render method.
+
+For example if you have a partial template in filepath `partials/partial.erb`:
+
+    This is a partial, Hello <%= name %>
+
+And your template is
+
+    My favourite colour is <%= colour %>
+    <%= render 'partials/partial.erb' %>
+
+And you execute the command as
+
+    echo '{ "colour": "purple", "name": "Jonathan" }' | template_renderer path_to_my_template
+
+You will produce
+
+    { "rendered": "My favourite colour is purple\nThis is a partial, Hello Jonathan\n" }
+
 ## ERB Template notes
 
 Trim mode is enabled and the trim character is a hyphen `-`.
diff --git a/Rakefile b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "bundler/gem_tasks"
 require "rspec/core/rake_task"
 
diff --git a/examples/Gemfile b/examples/Gemfile
@@ -1 +1,3 @@
+# frozen_string_literal: true
+
 gem "terraform-template-renderer", path: "../"
diff --git a/examples/Gemfile.lock b/examples/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: ..
   specs:
-    terraform-template-renderer (0.2.0)
+    terraform-template-renderer (0.3.0)
 
 GEM
   remote: https://rubygems.org/
diff --git a/examples/simple_partials/partials/string1.erb b/examples/simple_partials/partials/string1.erb
@@ -0,0 +1,2 @@
+First partial <%= @partial_key_1 %>
+<%= render "partials/string2.erb" -%>
diff --git a/examples/simple_partials/partials/string2.erb b/examples/simple_partials/partials/string2.erb
@@ -0,0 +1 @@
+Second partial <%= @partial_key_2 %>
diff --git a/examples/simple_partials/simple_partials.erb b/examples/simple_partials/simple_partials.erb
@@ -0,0 +1,3 @@
+KEY1 [<%=@key1%>]
+KEY2 [<%=@key2%>]
+<%= render "partials/string1.erb" -%>
diff --git a/examples/simple_partials/simple_partials.tf b/examples/simple_partials/simple_partials.tf
@@ -0,0 +1,23 @@
+terraform {
+  required_version = "~> 0.11.1"
+}
+
+provider "external" {
+  version = "~> 1.0.0"
+}
+
+data "external" "simple_partials" {
+  program = ["bundle", "exec", "render-template", "simple_partials.erb"]
+
+  query {
+    key1 = "value1"
+    key2 = "value2"
+    partial_key_1 = "partial_value_1"
+    partial_key_2 = "partial_value_2"
+  }
+}
+
+resource "local_file" "simple_partials" {
+  content = "${data.external.simple_partials.result.rendered}"
+  filename = "sample_output"
+}
diff --git a/exe/render-template b/exe/render-template
@@ -1,15 +1,17 @@
 #!/usr/bin/env ruby
 
+# frozen_string_literal: true
+
 require "bundler/setup"
 require "json"
 require_relative "../lib/terraform_template_renderer"
 
 def help
-  puts <<~EOF
+  puts <<~HELP
     Usage: render-template <path_to_erb_template>
 
     Reads json blob with params from STDIN
-  EOF
+  HELP
 end
 
 if ARGV.empty?
@@ -24,15 +26,15 @@ if ["-h", "--help", "-help", "help"].include?(template_path)
   exit 0
 end
 
-unless File.exist?(template_path)
+unless File.file?(template_path)
   STDERR.puts "ERB Template #{template_path} does not exist"
   exit 2
 end
 
 template = File.read(template_path)
 json_params = STDIN.read
 
-renderer = TerraformTemplateRenderer::Renderer.new(template)
+renderer = TerraformTemplateRenderer::Renderer.new(template, File.dirname(template_path))
 rendered_template = renderer.render(json_params)
 json_output = { rendered: rendered_template }.to_json
 puts json_output
diff --git a/lib/terraform_template_renderer.rb b/lib/terraform_template_renderer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative "terraform_template_renderer/binding"
 require_relative "terraform_template_renderer/renderer"
 require_relative "terraform_template_renderer/version"
diff --git a/lib/terraform_template_renderer/binding.rb b/lib/terraform_template_renderer/binding.rb
@@ -1,11 +1,28 @@
+# frozen_string_literal: true
+
 module TerraformTemplateRenderer
+  # Provides a Binding context which we can add arbitrary params to (which will become instance
+  # variables for the templates when they get rendered). Also provides a method to render
+  # partial templates which will pass through itself as the binding context for the partial
+  # template
   class Binding
+    def initialize(template_path)
+      @template_path = template_path
+    end
+
     def add_param(key, value)
       instance_variable_set("@#{key}", value)
     end
 
     def bind
       binding
     end
+
+    def render(partial_path)
+      path_to_partial = File.join(@template_path, partial_path)
+      renderer = Renderer.new(File.read(path_to_partial), @template_path)
+
+      renderer.render_with_binding(self)
+    end
   end
 end
diff --git a/lib/terraform_template_renderer/renderer.rb b/lib/terraform_template_renderer/renderer.rb
@@ -1,23 +1,35 @@
+# frozen_string_literal: true
+
 require "erb"
 require "json"
 
 module TerraformTemplateRenderer
+  # Renderer to remder an ERB template with variables taken from a json string instead of
+  # from the original binding
   class Renderer
-    def initialize(template)
+    def initialize(template, template_path)
       # The third argument enables trim mode using a hyphen
       @erb_template = ERB.new(template, nil, "-")
+      @template_path = template_path
     end
 
     # The passed in json_variables needs to be a JSON object (not array), all the keys will be used
     # as variables in the templates
     def render(json_variables)
-      @erb_template.result(template_binding(json_variables))
+      binding_ = template_binding(json_variables)
+      render_with_binding(binding_)
+    end
+
+    def render_with_binding(binding_)
+      @erb_template.result(binding_.bind)
     end
 
     private
 
     def template_binding(json_variables)
-      Binding.new.tap { |binding_object| add_params_to_object(binding_object, JSON.parse(json_variables)) }.bind
+      Binding.new(@template_path).tap do |binding_object|
+        add_params_to_object(binding_object, JSON.parse(json_variables))
+      end
     end
 
     def add_params_to_object(object, params)
diff --git a/lib/terraform_template_renderer/version.rb b/lib/terraform_template_renderer/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module TerraformTemplateRenderer
-  VERSION = "0.2.0"
+  VERSION = "0.3.0"
 end
diff --git a/spec/exe/render_template_spec.rb b/spec/exe/render_template_spec.rb
@@ -50,7 +50,21 @@
     end
   end
 
+  shared_examples :it_successfully_renders do
+    it "renders the template to stdout, nothing to stderr and exits successfully" do
+      expect(last_command_stopped.stderr).to eq("")
+      expect(last_command_stopped.stdout).to eq(File.read(rendered_path))
+      expect(last_command_stopped.exit_status).to eq(0)
+    end
+  end
+
   context "Successful run" do
+    before(:example) do
+      run("#{executable} #{template_path}")
+      last_command_started.stdin.write(json)
+      last_command_started.stdin.close
+    end
+
     context "with a simple template" do
       let(:template_path) { File.join(fixture_path, "simple_template.erb") }
       let(:rendered_path) { File.join(fixture_path, "simple_template.rendered") }
@@ -62,17 +76,22 @@
         }.to_json
       end
 
-      before(:example) do
-        run("#{executable} #{template_path}")
-        last_command_started.stdin.write(json)
-        last_command_started.stdin.close
-      end
+      it_behaves_like :it_successfully_renders
+    end
 
-      it "renders the template to stdout, nothing to stderr and exits successfully" do
-        expect(last_command_stopped.stdout).to eq(File.read(rendered_path))
-        expect(last_command_stopped.stderr).to eq("")
-        expect(last_command_stopped.exit_status).to eq(0)
+    context "with a template that includes partials" do
+      let(:template_path) { File.join(fixture_path, "template_with_partial.erb") }
+      let(:rendered_path) { File.join(fixture_path, "template_with_partial.rendered") }
+
+      let(:json) do
+        {
+          mykey1: "my_value1",
+          mykey2: "my_value2",
+          partialkey: "bar"
+        }.to_json
       end
+
+      it_behaves_like :it_successfully_renders
     end
   end
 end
diff --git a/spec/fixtures/partial.erb b/spec/fixtures/partial.erb
@@ -0,0 +1 @@
+var foo = '<%= @partialkey %>'
diff --git a/spec/fixtures/partial.rendered b/spec/fixtures/partial.rendered
@@ -0,0 +1 @@
+var foo = 'bar'
diff --git a/spec/fixtures/template_with_partial.erb b/spec/fixtures/template_with_partial.erb
@@ -0,0 +1,3 @@
+var thing = '<%= @mykey1 %>'
+<%= render "partial.erb" -%>
+var other = '<%= @mykey2 %>'
diff --git a/spec/fixtures/template_with_partial.rendered b/spec/fixtures/template_with_partial.rendered
@@ -0,0 +1 @@
+{"rendered":"var thing = 'my_value1'\nvar foo = 'bar'\nvar other = 'my_value2'\n"}
diff --git a/spec/lib/terraform_template_renderer/binding_spec.rb b/spec/lib/terraform_template_renderer/binding_spec.rb
@@ -1,7 +1,8 @@
 require "spec_helper"
 
 RSpec.describe TerraformTemplateRenderer::Binding do
-  subject(:binding) { described_class.new }
+  subject(:binding) { described_class.new(template_path) }
+  let(:template_path) { "spec/fixtures" }
   let(:key) { "my_key" }
   let(:value) { "my_value" }
 
@@ -30,4 +31,13 @@
         not_to change { binding2.instance_variable_get("@test_variable") }.from("test_value_before_2")
     end
   end
+
+  describe "#render" do
+    let(:rendered) { File.read("spec/fixtures/partial.rendered") }
+
+    it "creates a renderer with the expected template" do
+      binding.add_param("partialkey", "bar")
+      expect(binding.render("partial.erb")).to eq(rendered)
+    end
+  end
 end
diff --git a/spec/lib/terraform_template_renderer/renderer_spec.rb b/spec/lib/terraform_template_renderer/renderer_spec.rb
@@ -2,7 +2,8 @@
 require "json"
 
 RSpec.describe TerraformTemplateRenderer::Renderer do
-  subject(:renderer) { described_class.new(template) }
+  subject(:renderer) { described_class.new(template, template_path) }
+  let(:template_path) { "spec/fixtures" }
 
   let(:template) { "var thing = '<%= @mykey1 %>'; var other = '<%= @mykey2 %>'" }
 
@@ -40,4 +41,32 @@
       end
     end
   end
+
+  describe "#render_with_binding" do
+    let(:template_binding) { TerraformTemplateRenderer::Binding.new(template_path) }
+
+    it "produces a rendered template completed with the variables passed in" do
+      template_binding.add_param("mykey1", "my_value1")
+      template_binding.add_param("mykey2", "my_value2")
+      expect(subject.render_with_binding(template_binding)).to eq(rendered_template)
+    end
+  end
+
+  context "with a partial in the template" do
+    let(:template) do
+      "<%= render 'partial.erb' %>"
+    end
+    let(:json_for_partial) do
+      {
+        mykey1: "my_value1",
+        mykey2: "my_value2",
+        partialkey: "bar"
+      }.to_json
+    end
+    let(:rendered_with_partial) { "var foo = 'bar'\n" }
+
+    it "renders the template including the partial" do
+      expect(subject.render(json_for_partial)).to eq(rendered_with_partial)
+    end
+  end
 end
diff --git a/terraform-template-renderer.gemspec b/terraform-template-renderer.gemspec
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative "lib/terraform_template_renderer/version"
 
 Gem::Specification.new do |spec|

-Original file line number
+Diff line change
@@ @@ -1,3 +1,5 @@ @@
 +# frozen_string_literal: true
++
 source "https://rubygems.org"
 gemspec
Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,5 @@`
	`1`	`+# frozen_string_literal: true`
	`2`	`+`
`1`	`3`	`require "bundler/gem_tasks"`
`2`	`4`	`require "rspec/core/rake_task"`
`3`	`5`
Original file line number	Diff line number	Diff line change
`@@ -1 +1,3 @@`
	`1`	`+# frozen_string_literal: true`
	`2`	`+`
`1`	`3`	`gem "terraform-template-renderer", path: "../"`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+First partial <%= @partial_key_1 %>`
	`2`	`+<%= render "partials/string2.erb" -%>`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+KEY1 [<%=@key1%>]`
	`2`	`+KEY2 [<%=@key2%>]`
	`3`	`+<%= render "partials/string1.erb" -%>`