feat: implement constraint directive

Author: MH4GF

.gitignore

@@ -9,3 +9,5 @@
 
 # rspec failure tracking
 .rspec_status
+
+.byebug_history

.rubocop.yml

@@ -1,5 +1,7 @@
 AllCops:
   TargetRubyVersion: 3.0.0
+  NewCops: enable
+  SuggestExtensions: false
 
 Style/StringLiterals:
   Enabled: true
@@ -11,3 +13,11 @@ Style/StringLiteralsInInterpolation:
 
 Layout/LineLength:
   Max: 120
+
+Metrics/BlockLength:
+  Exclude:
+    - "spec/**/*"
+
+Style/Documentation:
+  Enabled: false
+

Gemfile

@@ -4,8 +4,8 @@ source "https://rubygems.org"
 
 gemspec
 
+gem "byebug"
 gem "rake", "~> 13.0"
-
 gem "rspec", "~> 3.0"
-
+gem "rspec-json_matcher"
 gem "rubocop", "~> 1.21"

Gemfile.lock

@@ -2,12 +2,14 @@ PATH
   remote: .
   specs:
     graphql-constraint-directive (0.1.0)
-      graphql (~> 2.0, >= 2.0.16)
+      graphql (~> 2.0, < 3)
 
 GEM
   remote: https://rubygems.org/
   specs:
+    amazing_print (1.4.0)
     ast (2.4.2)
+    byebug (11.1.3)
     diff-lcs (1.5.0)
     graphql (2.0.16)
     json (2.6.2)
@@ -27,6 +29,9 @@ GEM
     rspec-expectations (3.12.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.12.0)
+    rspec-json_matcher (0.2.0)
+      amazing_print
+      json
     rspec-mocks (3.12.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.12.0)
@@ -50,9 +55,11 @@ PLATFORMS
   arm64-darwin-21
 
 DEPENDENCIES
+  byebug
   graphql-constraint-directive!
   rake (~> 13.0)
   rspec (~> 3.0)
+  rspec-json_matcher
   rubocop (~> 1.21)
 
 BUNDLED WITH

graphql-constraint-directive.gemspec

@@ -4,7 +4,7 @@ require_relative "lib/graphql/constraint/directive/version"
 
 Gem::Specification.new do |spec|
   spec.name = "graphql-constraint-directive"
-  spec.version = Graphql::Constraint::Directive::VERSION
+  spec.version = GraphQL::Constraint::Directive::VERSION
   spec.authors = ["MH4GF"]
   spec.email = ["[email protected]"]
 
@@ -31,5 +31,6 @@ Gem::Specification.new do |spec|
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "graphql", "~> 2.0", ">= 2.0.16"
+  spec.add_runtime_dependency "graphql", "~> 2.0", "< 3"
+  spec.metadata["rubygems_mfa_required"] = "true"
 end

lib/graphql/constraint/directive.rb

@@ -1,12 +1,16 @@
 # frozen_string_literal: true
 
 require_relative "directive/version"
+require_relative "directive/constraint"
 
-module Graphql
+module GraphQL
   module Constraint
     module Directive
       class Error < StandardError; end
-      # Your code goes here...
+
+      def self.use(schema_defn)
+        schema_defn.directive(Constraint)
+      end
     end
   end
 end

lib/graphql/constraint/directive/constraint.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "graphql"
+require "byebug"
+
+module GraphQL
+  module Constraint
+    module Directive
+      class Constraint < GraphQL::Schema::Directive
+        LENGTH = { min_length: :minimum, max_length: :maximum }.freeze
+
+        description "validate GraphQL fields"
+        argument :max_length, Int, required: false, description: "validate max length"
+        argument :min_length, Int, required: false, description: "validate min length"
+        locations INPUT_FIELD_DEFINITION
+
+        def initialize(owner, **arguments)
+          super
+          validates = validation_config(@arguments.keyword_arguments)
+          owner.validates(validates)
+        end
+
+        def validation_config(arguments)
+          {
+            length: arguments.filter { |key, _| LENGTH.key?(key) }.transform_keys { |key| LENGTH[key] }
+          }
+        end
+      end
+    end
+  end
+end

lib/graphql/constraint/directive/version.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-module Graphql
+module GraphQL
   module Constraint
     module Directive
       VERSION = "0.1.0"

spec/graphql/constraint/directive/constraint_spec.rb

@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+
+RSpec.describe GraphQL::Constraint::Directive::Constraint do
+  let(:query) do
+    <<~GRAPHQL
+      mutation($input: SampleMutationInput!) {
+        sample(input: $input) {
+          text
+          extraArgs
+        }
+      }
+    GRAPHQL
+  end
+
+  context "with violated" do
+    let(:expected) do
+      {
+        "data" => {
+          "sample" => nil
+        },
+        "errors" => [
+          {
+            "message" => message,
+            "locations" => [
+              {
+                "line" => 2,
+                "column" => 3
+              }
+            ],
+            "path" => [
+              "sample"
+            ]
+          }
+        ]
+      }
+    end
+
+    context "when min is violated" do
+      let(:variables) { { input: { text: "" } } }
+      let(:message) { "text is too short (minimum is 1)" }
+
+      it "is returns error" do
+        expect(Schema.execute(query: query, variables: variables).to_json).to be_json_as(expected)
+      end
+    end
+
+    context "when max is violated" do
+      let(:variables) { { input: { text: "wow" } } }
+      let(:message) { "text is too long (maximum is 2)" }
+
+      it "is returns error" do
+        expect(Schema.execute(query: query, variables: variables).to_json).to be_json_as(expected)
+      end
+    end
+  end
+
+  context "when valid argument" do
+    let(:variables) { { input: { text: "yo" } } }
+    let(:expected) do
+      {
+        "data" => {
+          "sample" => {
+            "text" => "yo",
+            "extraArgs" => nil
+          }
+        }
+      }
+    end
+
+    it "returns data" do
+      expect(Schema.execute(query: query, variables: variables).to_json).to be_json_as(expected)
+    end
+  end
+
+  context "with other arguments" do
+    let(:variables) { { input: { extraArgs: "foo" } } }
+    let(:expected) do
+      {
+        "data" => {
+          "sample" => {
+            "text" => nil,
+            "extraArgs" => "foo"
+          }
+        }
+      }
+    end
+
+    it "returns data" do
+      expect(Schema.execute(query: query, variables: variables).to_json).to be_json_as(expected)
+    end
+  end
+end

spec/graphql/constraint/directive_spec.rb

@@ -1,11 +1,7 @@
 # frozen_string_literal: true
 
-RSpec.describe Graphql::Constraint::Directive do
+RSpec.describe GraphQL::Constraint::Directive do
   it "has a version number" do
-    expect(Graphql::Constraint::Directive::VERSION).not_to be nil
-  end
-
-  it "does something useful" do
-    expect(false).to eq(true)
+    expect(GraphQL::Constraint::Directive::VERSION).not_to be nil
   end
 end

spec/spec_helper.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 require "graphql/constraint/directive"
+require "support/schema"
+require "rspec/json_matcher"
 
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
@@ -12,4 +14,6 @@
   config.expect_with :rspec do |c|
     c.syntax = :expect
   end
+
+  config.include RSpec::JsonMatcher
 end

spec/support/schema.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class BaseMutation < GraphQL::Schema::RelayClassicMutation
+end
+
+class SampleMutation < BaseMutation
+  argument :text, String, required: false,
+                          directives: { GraphQL::Constraint::Directive::Constraint => { min_length: 1, max_length: 2 } }
+  argument :extra_args, String, required: false
+
+  field :text, String, null: true
+  field :extra_args, String, null: true
+
+  def resolve(text: nil, extra_args: nil)
+    {
+      text: text,
+      extra_args: extra_args
+    }
+  end
+end
+
+class MutationType < GraphQL::Schema::Object
+  field :sample, mutation: SampleMutation
+end
+
+class Schema < GraphQL::Schema
+  mutation MutationType
+
+  use GraphQL::Constraint::Directive
+end