在rspec测试中检查WHERE子句

Question

我在rails中有一个命名作用域，我有一个名为Product的模型

class Product < ApplicationRecord
 scope :old_products, -> { where("tagged_with = ?","old") }
end

是否有任何主体遇到检查主题的过程，该主题使用活动记录中的where，并且可以检查命名范围实际持有的where子句是什么

在rspec spec/model/product_spec.rb中

describe Product do
  describe "checking scope clauses" do
  subject { Product.old_products }
    its(:where_clauses)   { should eq([
      "tagged_with = 'old'"
    ]) }
  end
  end
end

顺便说一句，我将rspec-2.89版本与rails-5版本一起使用，因此我们可以检查和验证where子句

Answer 1

我个人认为检查一个作用域的返回SQL是不够的。我测试old_products的方式是：

describe Product do
  describe "scopes" do
    describe "old_products" do
      let!(:old_product) {Product.create(tagged_with: 'old')}
      let!(:not_old_product) {Product.create(tagged_with: 'sth_else')}
      subject { Product.old_products }

      it "returns the product(s) with tagged_with = old" do
        expect(subject).to eq([old_product])
      end
    end
  end
end

如果您仍然想检查返回查询，可以尝试一下：

it "..." do
  expect(subject.to_sql).to eq("SELECT \"products\".* FROM \"products\" WHERE \"products\".\"tagged_with\" = 'old'")
end

Answer 2

# This is better, more readable syntax for scope declaration
class Product < ApplicationRecord
  scope :old_products, -> { where(tagged_with: 'old') }
end

# Something like this would work
describe Product do
  context 'scopes' do
    # Set up something that will always be excluded from the scopes
    let!(:product)     { create :product }
    let!(:scoped_list) { create :product, 3, tagged_with: tag }

    shared_examples_for 'returns scoped records' do
      # This should work with shoulda-matchers 
      # (https://github.com/thoughtbot/shoulda-matchers)
      # Could also not use subject and do something like:
      #   expect(
      #     described_class.send(scope_name.to_sym) 
      #   ).to contain_exactly(scoped_list)
      # and declare let(:scope_name) in your describe blocks
      it 'returns scoped products' do
        should contain_exactly(scoped_list)
      end
    end

    describe '.old_products' do
      subject(:old_products) { described_class.old_products }

      let(:tag) { 'old' }

      it_behaves_like 'returns scoped records'
    end

    describe '.other_scope' do
      subject(:other_scope) { described_class.other_scope }

      let(:tag) { 'other_tag' }

      it_behaves_like 'returns scoped records'
    end
  end
end

• 测试实际的SQL没有任何价值--它是由Rails生成的；您要测试的是您的作用域是否返回了正确的对象
• 在声明作用域测试块时，我会使用context而不是describe，因为您不是在描述类或实例方法
• 使用单引号而不是双引号(除非您正在进行字符串插值) --它的性能更好

<>H110如果您在项目的早期，并且每个产品只有一个标记，我还会将tagged_with列重命名为tag

Answer 3

describe Product do
  describe "checking scope clauses" do
  subject { Product.old_products }
    expect(subject.values[:where].instance_values['predicates'].to eq(["tagged_with = 'old'"])
  end
end