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方法
A

实例公共方法

assert_changes(expression, message = nil, from: UNTRACKED, to: UNTRACKED, &block)

断言在调用传入的块之前和之后，表达式的计算结果发生了变化。

assert_changes 'Status.all_good?' do
  post :create, params: { status: { ok: false } }
end

您可以将块作为字符串传递，以便在块的上下文中进行评估。也可以为块传递一个 lambda。

assert_changes -> { Status.all_good? } do
  post :create, params: { status: { ok: false } }
end

此断言对于测试副作用很有用。传入的块可以是任何可以转换为字符串的对象（使用 to_s）。

assert_changes :@object do
  @object = 42
end

可以使用关键字参数 :from 和 :to 来指定预期的初始值和执行块后的预期值。比较使用 case equality (===)，这意味着您可以指定模式或类。

# Exact value match
assert_changes :@object, from: nil, to: :foo do
  @object = :foo
end

# Case equality
assert_changes -> { user.token }, to: /\w{32}/ do
  user.generate_token
end

# Type check
assert_changes -> { current_error }, from: nil, to: RuntimeError do
  raise "Oops"
end

可以指定错误消息。

assert_changes -> { Status.all_good? }, 'Expected the status to be bad' do
  post :create, params: { status: { incident: true } }
end

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 211
def assert_changes(expression, message = nil, from: UNTRACKED, to: UNTRACKED, &block)
  exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }

  before = exp.call
  retval = _assert_nothing_raised_or_warn("assert_changes", &block)

  unless from == UNTRACKED
    rich_message = -> do
      error = "Expected change from #{from.inspect}, got #{before.inspect}"
      error = "#{message}.\n#{error}" if message
      error
    end
    assert from === before, rich_message
  end

  after = exp.call

  rich_message = -> do
    code_string = expression.respond_to?(:call) ? _callable_to_source_string(expression) : expression
    error = "`#{code_string}` didn't change"
    error = "#{error}. It was already #{to.inspect}" if before == to
    error = "#{message}.\n#{error}" if message
    error
  end
  refute_equal before, after, rich_message

  unless to == UNTRACKED
    rich_message = -> do
      error = "Expected change to #{to.inspect}, got #{after.inspect}\n"
      error = "#{message}.\n#{error}" if message
      error
    end
    assert to === after, rich_message
  end

  retval
end

assert_difference(expression, *args, &block)

测试由所产生的块计算出的表达式的值与之前之间的数值差异。

assert_difference 'Article.count' do
  post :create, params: { article: {...} }
end

传入并计算一个任意表达式。

assert_difference 'Article.last.comments(:reload).size' do
  post :create, params: { comment: {...} }
end

可以指定任意的正数或负数差值。默认值为 1。

assert_difference 'Article.count', -1 do
  post :delete, params: { id: ... }
end

可以传入并计算表达式数组。

assert_difference [ 'Article.count', 'Post.count' ], 2 do
  post :create, params: { article: {...} }
end

可以传入并计算表达式/数值差值哈希。

assert_difference({ 'Article.count' => 1, 'Notification.count' => 2 }) do
  post :create, params: { article: {...} }
end

可以传入并计算 lambda、lambda 列表或 lambda/数值差值哈希。

assert_difference ->{ Article.count }, 2 do
  post :create, params: { article: {...} }
end

assert_difference [->{ Article.count }, ->{ Post.count }], 2 do
  post :create, params: { article: {...} }
end

assert_difference ->{ Article.count } => 1, ->{ Notification.count } => 2 do
  post :create, params: { article: {...} }
end

可以指定错误消息。

assert_difference 'Article.count', -1, 'An Article should be destroyed' do
  post :delete, params: { id: ... }
end

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 105
def assert_difference(expression, *args, &block)
  expressions =
    if expression.is_a?(Hash)
      message = args[0]
      expression
    else
      difference = args[0] || 1
      message = args[1]
      Array(expression).index_with(difference)
    end

  exps = expressions.keys.map { |e|
    e.respond_to?(:call) ? e : lambda { eval(e, block.binding) }
  }
  before = exps.map(&:call)

  retval = _assert_nothing_raised_or_warn("assert_difference", &block)

  expressions.zip(exps, before) do |(code, diff), exp, before_value|
    actual = exp.call
    rich_message = -> do
      code_string = code.respond_to?(:call) ? _callable_to_source_string(code) : code
      error = "`#{code_string}` didn't change by #{diff}, but by #{actual - before_value}"
      error = "#{message}.\n#{error}" if message
      error
    end
    assert_equal(before_value + diff, actual, rich_message)
  end

  retval
end

assert_no_changes(expression, message = nil, from: UNTRACKED, &block)

断言在调用传入的块之前和之后，表达式的计算结果没有发生变化。

assert_no_changes 'Status.all_good?' do
  post :create, params: { status: { ok: true } }
end

提供可选的关键字参数 :from 来指定预期的初始值。比较使用 case equality (===)，这意味着您可以指定模式或类。

# Exact value match
assert_no_changes -> { Status.all_good? }, from: true do
  post :create, params: { status: { ok: true } }
end

# Case equality
assert_no_changes -> { user.token }, from: /\w{32}/ do
  user.touch
end

# Type check
assert_no_changes -> { current_error }, from: RuntimeError do
  retry_operation
end

可以指定错误消息。

assert_no_changes -> { Status.all_good? }, 'Expected the status to be good' do
  post :create, params: { status: { ok: false } }
end

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 280
def assert_no_changes(expression, message = nil, from: UNTRACKED, &block)
  exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }

  before = exp.call
  retval = _assert_nothing_raised_or_warn("assert_no_changes", &block)

  unless from == UNTRACKED
    rich_message = -> do
      error = "Expected initial value of #{from.inspect}, got #{before.inspect}"
      error = "#{message}.\n#{error}" if message
      error
    end
    assert from === before, rich_message
  end

  after = exp.call

  rich_message = -> do
    code_string = expression.respond_to?(:call) ? _callable_to_source_string(expression) : expression
    error = "`#{code_string}` changed"
    error = "#{message}.\n#{error}" if message
    error
  end

  if before.nil?
    assert_nil after, rich_message
  else
    assert_equal before, after, rich_message
  end

  retval
end

assert_no_difference(expression, message = nil, &block)

断言在调用传入的块之前和之后，表达式的数值计算结果没有发生变化。

assert_no_difference 'Article.count' do
  post :create, params: { article: invalid_attributes }
end

可以传入并计算 lambda。

assert_no_difference -> { Article.count } do
  post :create, params: { article: invalid_attributes }
end

可以指定错误消息。

assert_no_difference 'Article.count', 'An Article should not be created' do
  post :create, params: { article: invalid_attributes }
end

也可以传入并计算表达式数组。

assert_no_difference [ 'Article.count', -> { Post.count } ] do
  post :create, params: { article: invalid_attributes }
end

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 161
def assert_no_difference(expression, message = nil, &block)
  assert_difference expression, 0, message, &block
end

assert_not(object, message = nil)

断言一个表达式不是真值。如果 object 是 nil 或 false，则断言通过。“真值”意味着“在条件中被视为真”，例如 if foo。

assert_not nil    # => true
assert_not false  # => true
assert_not 'foo'  # => Expected "foo" to be nil or false

可以指定错误消息。

assert_not foo, 'foo should be false'

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 21
def assert_not(object, message = nil)
  message ||= -> { "Expected #{mu_pp(object)} to be nil or false" }
  assert !object, message
end

assert_nothing_raised()

断言块不应引发异常。

如果所传入块中的代码计算没有引发异常，则断言通过。

assert_nothing_raised do
  perform_service(param: 'no_exception')
end

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 48
def assert_nothing_raised
  yield.tap { assert(true) }
rescue => error
  raise Minitest::UnexpectedError.new(error)
end

assert_raise(*exp, match: nil, &block)

别名：assert_raises

assert_raises(*exp, match: nil, &block)

断言一个块引发了 exp 中的异常之一。这是标准 Minitest 断言方法的增强，增加了测试错误消息的能力。

assert_raises(ArgumentError, match: /incorrect param/i) do
  perform_service(param: 'exception')
end
也别名为：assert_raise

源码: 显示 | 在 GitHub 上

# File activesupport/lib/active_support/testing/assertions.rb, line 34
def assert_raises(*exp, match: nil, &block)
  error = super(*exp, &block)
  assert_match(match, error.message) if match
  error
end