redundant_merge_spec.rb

# frozen_string_literal: true

RSpec.describe RuboCop::Cop::Performance::RedundantMerge, :config do
  let(:cop_config) do
    { 'MaxKeyValuePairs' => 2 }
  end

  it 'autocorrects hash.merge!(a: 1)' do
    new_source = autocorrect_source('hash.merge!(a: 1)')
    expect(new_source).to eq 'hash[:a] = 1'
  end

  it 'autocorrects hash.merge!("abc" => "value")' do
    new_source = autocorrect_source('hash.merge!("abc" => "value")')
    expect(new_source).to eq 'hash["abc"] = "value"'
  end

  context 'when receiver is a local variable' do
    it 'autocorrects hash.merge!(a: 1, b: 2)' do
      new_source = autocorrect_source(<<~RUBY)
        hash = {}
        hash.merge!(a: 1, b: 2)
      RUBY
      expect(new_source).to eq(<<~RUBY)
        hash = {}
        hash[:a] = 1
        hash[:b] = 2
      RUBY
    end
  end

  context 'when receiver is a method call' do
    it "doesn't autocorrect hash.merge!(a: 1, b: 2)" do
      new_source = autocorrect_source('hash.merge!(a: 1, b: 2)')
      expect(new_source).to eq('hash.merge!(a: 1, b: 2)')
    end
  end

  # FIXME: `undefined method `[]' for nil` occurs Prism 0.24.0. It has been resolved in
  # the development line. This will be resolved in Prism > 0.24.0 and higher releases.
  context 'when receiver is implicit', broken_on: :prism do
    it "doesn't autocorrect" do
      new_source = autocorrect_source('merge!(foo: 1, bar: 2)')
      expect(new_source).to eq('merge!(foo: 1, bar: 2)')
    end
  end

  context 'when any argument is a double splat' do
    it 'does not register an offense when the only argument is adouble splat' do
      expect_no_offenses(<<~RUBY)
        foo.merge!(**bar)
      RUBY
    end

    it 'does not register an offense when there are multiple arguments and at least one is a double splat' do
      expect_no_offenses(<<~RUBY)
        foo.merge!(baz: qux, **bar)
      RUBY
    end
  end

  context 'when internal to each_with_object' do
    it 'autocorrects when the receiver is the object being built' do
      source = <<~RUBY
        foo.each_with_object({}) do |f, hash|
          hash.merge!(a: 1, b: 2)
        end
      RUBY
      new_source = autocorrect_source(source)

      expect(new_source).to eq(<<~RUBY)
        foo.each_with_object({}) do |f, hash|
          hash[:a] = 1
          hash[:b] = 2
        end
      RUBY
    end

    it 'autocorrects when the receiver is the object being built when merge! is the last statement' do
      source = <<~RUBY
        foo.each_with_object({}) do |f, hash|
          some_method
          hash.merge!(a: 1, b: 2)
        end
      RUBY
      new_source = autocorrect_source(source)

      expect(new_source).to eq(<<~RUBY)
        foo.each_with_object({}) do |f, hash|
          some_method
          hash[:a] = 1
          hash[:b] = 2
        end
      RUBY
    end

    it 'autocorrects when the receiver is the object being built when merge! is not the last statement' do
      source = <<~RUBY
        foo.each_with_object({}) do |f, hash|
          hash.merge!(a: 1, b: 2)
          why_are_you_doing_this?
        end
      RUBY
      new_source = autocorrect_source(source)

      expect(new_source).to eq(<<~RUBY)
        foo.each_with_object({}) do |f, hash|
          hash[:a] = 1
          hash[:b] = 2
          why_are_you_doing_this?
        end
      RUBY
    end

    it 'does not register an offense when merge! is being assigned inside each_with_object' do
      expect_no_offenses(<<~RUBY)
        foo.each_with_object({}) do |f, hash|
          changes = hash.merge!(a: 1, b: 2)
          why_are_you_doing_this?
        end
      RUBY
    end

    it 'autocorrects when receiver uses element reference to the object built by each_with_object' do
      source = <<~RUBY
        foo.each_with_object(bar) do |f, hash|
          hash[:a].merge!(b: "")
        end
      RUBY
      new_source = autocorrect_source(source)

      expect(new_source).to eq(<<~RUBY)
        foo.each_with_object(bar) do |f, hash|
          hash[:a][:b] = ""
        end
      RUBY
    end

    it 'autocorrects when receiver uses multiple element references to the object built by each_with_object' do
      source = <<~RUBY
        foo.each_with_object(bar) do |f, hash|
          hash[:a][:b].merge!(c: "")
        end
      RUBY
      new_source = autocorrect_source(source)

      expect(new_source).to eq(<<~RUBY)
        foo.each_with_object(bar) do |f, hash|
          hash[:a][:b][:c] = ""
        end
      RUBY
    end

    it 'autocorrects merge! called on any method on the object built by each_with_object' do
      source = <<~RUBY
        foo.each_with_object(bar) do |f, hash|
          hash.bar.merge!(c: "")
        end
      RUBY
      new_source = autocorrect_source(source)

      expect(new_source).to eq(<<~RUBY)
        foo.each_with_object(bar) do |f, hash|
          hash.bar[:c] = ""
        end
      RUBY
    end
  end

  %w[if unless while until].each do |kw|
    context "when there is a modifier #{kw}, and more than 1 pair" do
      it "autocorrects it to an #{kw} block" do
        new_source = autocorrect_source(
          <<~RUBY
            hash = {}
            hash.merge!(a: 1, b: 2) #{kw} condition1 && condition2
          RUBY
        )
        expect(new_source).to eq(<<~RUBY)
          hash = {}
          #{kw} condition1 && condition2
            hash[:a] = 1
            hash[:b] = 2
          end
        RUBY
      end

      context 'when original code was indented' do
        it 'maintains proper indentation' do
          new_source = autocorrect_source(
            <<~RUBY
              hash = {}
              begin
                hash.merge!(a: 1, b: 2) #{kw} condition1
              end
            RUBY
          )
          expect(new_source).to eq(<<~RUBY)
            hash = {}
            begin
              #{kw} condition1
                hash[:a] = 1
                hash[:b] = 2
              end
            end
          RUBY
        end
      end
    end
  end

  context 'when code is indented, and there is more than 1 pair' do
    it 'indents the autocorrected code properly' do
      new_source = autocorrect_source(<<~RUBY)
        hash = {}
        begin
          hash.merge!(a: 1, b: 2)
        end
      RUBY
      expect(new_source).to eq(<<~RUBY)
        hash = {}
        begin
          hash[:a] = 1
          hash[:b] = 2
        end
      RUBY
    end
  end

  it 'does not register an offense when using an empty hash argument' do
    expect_no_offenses(<<~RUBY)
      foo.merge!({})
    RUBY
  end

  it "doesn't register an error when return value is used" do
    expect_no_offenses(<<~RUBY)
      variable = hash.merge!(a: 1)
      puts variable
    RUBY
  end

  it 'formats the error message correctly for hash.merge!(a: 1)' do
    expect_offense(<<~RUBY)
      hash.merge!(a: 1)
      ^^^^^^^^^^^^^^^^^ Use `hash[:a] = 1` instead of `hash.merge!(a: 1)`.
    RUBY
  end

  context 'with MaxKeyValuePairs of 1' do
    let(:cop_config) do
      { 'MaxKeyValuePairs' => 1 }
    end

    it "doesn't register errors for multi-value hash merges" do
      expect_no_offenses(<<~RUBY)
        hash = {}
        hash.merge!(a: 1, b: 2)
      RUBY
    end
  end

  context 'when MaxKeyValuePairs is set to nil' do
    let(:cop_config) do
      { 'MaxKeyValuePairs' => nil }
    end

    it 'does not raise `TypeError`' do
      expect_offense(<<~RUBY)
        hash = {}
        hash.merge!(a: 1, b: 2)
        ^^^^^^^^^^^^^^^^^^^^^^^ Use `hash[:a] = 1; hash[:b] = 2` instead of `hash.merge!(a: 1, b: 2)`.
      RUBY
    end
  end
end