Class: CapybaraScreenshotDiff::ScreenshotAssertion

Inherits:
Object
  • Object
show all
Defined in:
lib/capybara_screenshot_diff/screenshot_assertion.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, **args) {|_self| ... } ⇒ ScreenshotAssertion

Returns a new instance of ScreenshotAssertion.

Yields:

  • (_self)

Yield Parameters:



10
11
12
13
14
15
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 10

def initialize(name, **args, &block)
  @name = name
  @args = args

  yield(self) if block_given?
end

Instance Attribute Details

#args ⇒ Object (readonly)

Returns the value of attribute args.



7
8
9
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 7

def args
  @args
end

#caller ⇒ Object

Returns the value of attribute caller.



8
9
10
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 8

def caller
  @caller
end

#compare ⇒ Object

Returns the value of attribute compare.



8
9
10
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 8

def compare
  @compare
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



7
8
9
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 7

def name
  @name
end

Class Method Details

.assert_image_not_changed(backtrace, name, comparison) ⇒ String?

Note:

This method is used internally to verify individual screenshots.

Asserts that an image has not changed compared to its baseline.

Parameters:

  • backtrace (Array(String)) —

    The caller context, used for error reporting.

  • name (String) —

    The name of the screenshot being verified.

  • comparison (Object) —

    The comparison object containing the result and details of the comparison.

Returns:

  • (String, nil) —

    Returns an error message if the screenshot differs from the baseline, otherwise nil.



59
60
61
62
63
64
65
66
67
68
69
70
71
72
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 59

def self.assert_image_not_changed(backtrace, name, comparison)
  result = comparison.different?

  # Cleanup after comparisons
  if !result && comparison.base_image_path.exist?
    FileUtils.mv(comparison.base_image_path, comparison.image_path, force: true)
  elsif !comparison.dimensions_changed?
    FileUtils.rm_rf(comparison.base_image_path)
  end

  return unless result

  "Screenshot does not match for '#{name}': #{comparison.error_message}\n#{backtrace.join("\n")}"
end

.from(screenshot_job) ⇒ Object 



17
18
19
20
21
22
23
24
25
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 17

def self.from(screenshot_job)
  return screenshot_job if screenshot_job.is_a?(ScreenshotAssertion)

  caller, name, compare = screenshot_job
  ScreenshotAssertion.new(name).tap do |it|
    it.caller = caller
    it.compare = compare
  end
end

.verify_screenshots!(screenshots) ⇒ Array?

Note:

This method is typically called at the end of a test to assert all screenshots are as expected.

Verifies that all scheduled screenshots do not show any unintended differences.

Parameters:

  • screenshots (Array(Array(Array(String), String, ImageCompare))) —

    The list of match screenshots jobs. Defaults to all screenshots taken during the test.

Returns:

  • (Array, nil) —

    Returns an array of error messages if there are screenshot differences, otherwise nil.



38
39
40
41
42
43
44
45
46
47
48
49
50
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 38

def self.verify_screenshots!(screenshots)
  return unless ::Capybara::Screenshot.active? && ::Capybara::Screenshot::Diff.fail_on_difference

  test_screenshot_errors = screenshots.map do |assertion|
    assertion.validate
  end

  test_screenshot_errors.compact!

  test_screenshot_errors.empty? ? nil : test_screenshot_errors
ensure
  screenshots&.clear
end

Instance Method Details

#validate ⇒ Object 



27
28
29
30
31
 
# File 'lib/capybara_screenshot_diff/screenshot_assertion.rb', line 27

def validate
  return unless compare

  self.class.assert_image_not_changed(caller, name, compare)
end