misc(filters-contracts): Define contracts to validate query objects filters

Gemfile

@@ -15,6 +15,7 @@ gem 'puma', '~> 6.4'
 gem 'rails', '~> 7.1.3.4'
 gem 'redis'
 gem 'sidekiq'
+gem 'dry-validation'
 
 # Security
 gem 'bcrypt'

Gemfile.lock

@@ -193,6 +193,39 @@ GEM
     docile (1.4.1)
     dotenv (3.1.2)
     drb (2.2.1)
+    dry-configurable (1.2.0)
+      dry-core (~> 1.0, < 2)
+      zeitwerk (~> 2.6)
+    dry-core (1.0.1)
+      concurrent-ruby (~> 1.0)
+      zeitwerk (~> 2.6)
+    dry-inflector (1.1.0)
+    dry-initializer (3.1.1)
+    dry-logic (1.5.0)
+      concurrent-ruby (~> 1.0)
+      dry-core (~> 1.0, < 2)
+      zeitwerk (~> 2.6)
+    dry-schema (1.13.4)
+      concurrent-ruby (~> 1.0)
+      dry-configurable (~> 1.0, >= 1.0.1)
+      dry-core (~> 1.0, < 2)
+      dry-initializer (~> 3.0)
+      dry-logic (>= 1.4, < 2)
+      dry-types (>= 1.7, < 2)
+      zeitwerk (~> 2.6)
+    dry-types (1.7.2)
+      bigdecimal (~> 3.0)
+      concurrent-ruby (~> 1.0)
+      dry-core (~> 1.0)
+      dry-inflector (~> 1.0)
+      dry-logic (~> 1.4)
+      zeitwerk (~> 2.6)
+    dry-validation (1.10.0)
+      concurrent-ruby (~> 1.0)
+      dry-core (~> 1.0, < 2)
+      dry-initializer (~> 3.0)
+      dry-schema (>= 1.12, < 2)
+      zeitwerk (~> 2.6)
     erubi (1.13.0)
     execjs (2.9.1)
     factory_bot (6.4.6)
@@ -892,6 +925,7 @@ DEPENDENCIES
   debug
   discard (~> 1.2)
   dotenv
+  dry-validation
   factory_bot_rails
   faker
   gocardless_pro (~> 2.34)

app/contracts/billable_metrics_query_filters_contract.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class BillableMetricsQueryFiltersContract < Dry::Validation::Contract
+  params do
+    required(:filters).hash do
+      optional(:recurring).filled(:bool)
+      optional(:aggregation_types).array(:string, included_in?: %w[max_agg count_agg])
+    end
+
+    optional(:search_term).maybe(:string)
+  end
+end

app/queries/base_query.rb

@@ -22,6 +22,19 @@ def initialize(organization:, pagination: DEFAULT_PAGINATION_PARAMS, filters: {}
 
   attr_reader :organization, :pagination_params, :filters, :search_term, :order
 
+  def validate_filters
+    contract_class_name = "#{self.class.name}FiltersContract"
+    contract = Object.const_get(contract_class_name).new
+    validation_result = contract.call(filters: filters.to_h, search_term:)
+
+    unless validation_result.success?
+      errors = validation_result.errors.to_h
+      result.validation_failure!(errors:)
+    end
+
+    result
+  end
+
   def pagination
     return if pagination_params.blank?
 

app/queries/billable_metrics_query.rb

@@ -2,6 +2,8 @@
 
 class BillableMetricsQuery < BaseQuery
   def call
+    return result unless validate_filters.success?
+
     metrics = base_scope.result
     metrics = paginate(metrics)
     metrics = metrics.order(created_at: :desc)

spec/contracts/billable_metrics_query_filters_contract_spec.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe BillableMetricsQueryFiltersContract, type: :contract do
+  subject(:result) { described_class.new.call(filters:, search_term:) }
+
+  let(:filters) { {} }
+  let(:search_term) { nil }
+
+  context "when filters are valid" do
+    let(:filters) do
+      {
+        recurring: true,
+        aggregation_types: ["max_agg", "count_agg"]
+      }
+    end
+
+    it "is valid" do
+      expect(result.success?).to be(true)
+    end
+  end
+
+  context "when search_term is provided and valid" do
+    let(:search_term) { "valid_search_term" }
+
+    it "is valid" do
+      expect(result.success?).to be(true)
+    end
+  end
+
+  context "when search_term is invalid" do
+    let(:search_term) { 12345 }
+
+    it "is invalid" do
+      expect(result.success?).to be(false)
+      expect(result.errors.to_h).to include(search_term: ["must be a string"])
+    end
+  end
+
+  context "when filters are invalid" do
+    shared_examples "an invalid filter" do |filter, value, error_message|
+      let(:filters) { {filter => value} }
+
+      it "is invalid when #{filter} is set to #{value.inspect}" do
+        expect(result.success?).to be(false)
+        expect(result.errors.to_h).to include(filters: {filter => error_message})
+      end
+    end
+
+    it_behaves_like "an invalid filter", :recurring, nil, ["must be filled"]
+    it_behaves_like "an invalid filter", :recurring, "not_a_bool", ["must be boolean"]
+
+    it_behaves_like "an invalid filter", :aggregation_types, nil, ["must be an array"]
+    it_behaves_like "an invalid filter", :aggregation_types, "not_an_array", ["must be an array"]
+    it_behaves_like "an invalid filter", :aggregation_types, [1], {0 => ["must be a string"]}
+    it_behaves_like "an invalid filter", :aggregation_types, ["invalid_type"], {0 => ["must be one of: max_agg, count_agg"]}
+  end
+end

spec/queries/billable_metrics_query_spec.rb

@@ -37,6 +37,21 @@
     end
   end
 
+  context "when filters validation fails" do
+    let(:filters) do
+      {
+        recurring: "unexpected_value",
+        aggregation_types: ["unexpected_value"]
+      }
+    end
+
+    it "captures all validation errors" do
+      expect(result).not_to be_success
+      expect(result.error.messages[:filters][:recurring]).to include("must be boolean")
+      expect(result.error.messages[:filters][:aggregation_types][0]).to include("must be one of: max_agg, count_agg")
+    end
+  end
+
   context 'with pagination' do
     let(:pagination) { {page: 2, limit: 3} }