refactor: exact matching

CHANGELOG.md

@@ -2,6 +2,22 @@
 
 ## master
 
+- Added ability to specify the exact number of expected queries when using constant matchers. ([@akostadinov][], [@palkan][])
+
+For RSpec, you can add the `.exactly` modifier:
+
+```ruby
+expect { get :index }.to perform_constant_number_of_queries.exactly(1)
+```
+
+For Minitest, you can provide the expected number of queries as the first argument:
+
+```ruby
+assert_perform_constant_number_of_queries(0, **options) do
+  get :index
+end
+```
+
 - **Require Ruby 2.7+**.
 
 ## 0.6.2 (2021-10-26)
@@ -46,3 +62,4 @@ Could be specified via `NPLUSONE_BACKTRACE` env var.
 [@palkan]: https://github.com/palkan
 [@caalberts]: https://github.com/caalberts
 [@andrewhampton]: https://github.com/andrewhampton
+[@akostadinov]: https://github.com/akostadinov

README.md

@@ -112,6 +112,9 @@ expect { get :index }.to perform_constant_number_of_queries.matching(/INSERT/)
 
 # You can also provide custom scale factors
 expect { get :index }.to perform_constant_number_of_queries.with_scale_factors(10, 100)
+
+# You can specify the exact number of expected queries
+expect { get :index }.to perform_constant_number_of_queries.exactly(1)
 ```
 
 #### Using scale factor in spec
@@ -214,6 +217,14 @@ assert_perform_constant_number_of_queries(
 end
 ```
 
+For the constant matcher, you can also specify the expected number of queries as the first argument:
+
+```ruby
+assert_perform_constant_number_of_queries(2, populate: populate) do
+  get :index
+end
+```
+
 It's possible to specify a filter via `NPLUSONE_FILTER` env var, e.g.:
 
 ```ruby

lib/n_plus_one_control/minitest.rb

@@ -5,31 +5,8 @@
 module NPlusOneControl
   # Minitest assertions
   module MinitestHelper
-    def assert_number_of_queries(
-      number,
-      populate: nil,
-      matching: nil,
-      warmup: nil
-    )
-
-      raise ArgumentError, "Block is required" unless block_given?
-
-      warming_up warmup
-
-      @executor = NPlusOneControl::Executor.new(
-        population: populate || population_method,
-        matching: (matching || NPlusOneControl.default_matching),
-        scale_factors: [1]
-      )
-
-      queries = @executor.call { yield }
-
-      counts = queries.map(&:last).map(&:size)
-
-      assert_equal number, counts.max, NPlusOneControl.failure_message(:number_of_queries, queries)
-    end
-
     def assert_perform_constant_number_of_queries(
+      exact = nil,
       populate: nil,
       matching: nil,
       scale_factors: nil,
@@ -50,7 +27,11 @@ def assert_perform_constant_number_of_queries(
 
       counts = queries.map(&:last).map(&:size)
 
-      assert counts.max == counts.min, NPlusOneControl.failure_message(:constant_queries, queries)
+      if exact
+        assert counts.all? { _1 == exact }, NPlusOneControl.failure_message(:number_of_queries, queries)
+      else
+        assert counts.max == counts.min, NPlusOneControl.failure_message(:constant_queries, queries)
+      end
     end
 
     def assert_perform_linear_number_of_queries(

lib/n_plus_one_control/rspec/matchers/perform_constant_number_of_queries.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-# rubocop:disable  Metrics/BlockLength
 ::RSpec::Matchers.define :perform_constant_number_of_queries do
   supports_block_expectations
 
@@ -43,7 +42,11 @@
 
     counts = @queries.map(&:last).map(&:size)
 
-    counts.max == (@exactly || counts.min)
+    if @exactly
+      counts.all? { _1 == @exactly }
+    else
+      counts.max == counts.min
+    end
   end
 
   match_when_negated do |_actual|
@@ -52,4 +55,3 @@
 
   failure_message { |_actual| NPlusOneControl.failure_message(@exactly ? :number_of_queries : :constant_queries, @queries) }
 end
-# rubocop:enable  Metrics/BlockLength

lib/n_plus_one_control/rspec/matchers/perform_linear_number_of_queries.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-# rubocop:disable  Metrics/BlockLength
 ::RSpec::Matchers.define :perform_linear_number_of_queries do |slope: 1|
   supports_block_expectations
 
@@ -50,4 +49,3 @@
 
   failure_message { |_actual| NPlusOneControl.failure_message(:linear_queries, @queries) }
 end
-# rubocop:enable  Metrics/BlockLength

tests/minitest_test.rb

@@ -2,42 +2,6 @@
 
 require_relative "test_helper"
 
-class TestMinitestSpecifiedQueries < Minitest::Test
-  def test_queries_match
-    populate = ->(n) { create_list(:post, n) }
-
-    assert_number_of_queries(1, populate: populate) do
-      Post.take
-    end
-  end
-
-  def test_queries_do_not_match
-    populate = ->(n) { create_list(:post, n) }
-
-    e = assert_raises Minitest::Assertion do
-      assert_number_of_queries(0, populate: populate) do
-        Post.take
-      end
-    end
-
-    assert_match "Expected to make the specified number of queries", e.message
-    assert_match "1 for N=1", e.message
-    assert_match(/posts \(SELECT\): 1$/, e.message)
-  end
-
-  def test_no_n_plus_one_error_with_matching
-    populate = ->(n) { create_list(:post, n) }
-
-    assert_number_of_queries(
-      1,
-      populate: populate,
-      matching: /posts/
-    ) do
-      Post.find_each { |p| p.user.name }
-    end
-  end
-end
-
 class TestMinitestConstantQueries < Minitest::Test
   def test_no_n_plus_one_error
     populate = ->(n) { create_list(:post, n) }
@@ -96,6 +60,40 @@ def test_no_n_plus_one_error_with_warmup
 
     assert warmed_up
   end
+
+  def test_exact_number_queries_match
+    populate = ->(n) { create_list(:post, n) }
+
+    assert_perform_constant_number_of_queries(1, populate: populate) do
+      Post.take
+    end
+  end
+
+  def test_exact_number_queries_do_not_match
+    populate = ->(n) { create_list(:post, n) }
+
+    e = assert_raises Minitest::Assertion do
+      assert_perform_constant_number_of_queries(0, populate: populate, scale_factors: [1]) do
+        Post.take
+      end
+    end
+
+    assert_match "Expected to make the specified number of queries", e.message
+    assert_match "1 for N=1", e.message
+    assert_match(/posts \(SELECT\): 1$/, e.message)
+  end
+
+  def test_exact_number_error_with_matching
+    populate = ->(n) { create_list(:post, n) }
+
+    assert_perform_constant_number_of_queries(
+      1,
+      populate: populate,
+      matching: /posts/
+    ) do
+      Post.find_each { |p| p.user.name }
+    end
+  end
 end
 
 class TestMinitestLinearQueries < Minitest::Test