module Minitest::Assertions

Minitest Assertions. All assertion methods accept a msg which is printed if the assertion fails.

Protocol: Nearly everything here boils up to assert, which expects to be able to increment an instance accessor named assertions. This is not provided by Assertions and must be provided by the thing including Assertions. See Minitest::Runnable for an example.

Public Class Methods

diff() click to toggle source

Returns the diff command to use in diff. Tries to intelligently figure out what diff to use.

# File lib/minitest/assertions.rb, line 27
def self.diff
  @diff = if (RbConfig::CONFIG["host_os"] =~ /mswin|mingw/ &&
              system("diff.exe", __FILE__, __FILE__)) then
            "diff.exe -u"
          elsif Minitest::Test.maglev? then
            "diff -u"
          elsif system("gdiff", __FILE__, __FILE__)
            "gdiff -u" # solaris and kin suck
          elsif system("diff", __FILE__, __FILE__)
            "diff -u"
          else
            nil
          end unless defined? @diff

  @diff
end
diff=(o) click to toggle source

Set the diff command to use in diff.

# File lib/minitest/assertions.rb, line 47
def self.diff= o
  @diff = o
end

Public Instance Methods

assert(test, msg = nil) click to toggle source

Fails unless test is truthy.

# File lib/minitest/assertions.rb, line 124
def assert test, msg = nil
  self.assertions += 1
  unless test then
    msg ||= "Failed assertion, no message given."
    msg = msg.call if Proc === msg
    raise Minitest::Assertion, msg
  end
  true
end
assert_empty(obj, msg = nil) click to toggle source

Fails unless obj is empty.

# File lib/minitest/assertions.rb, line 141
def assert_empty obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp(obj)} to be empty" }
  assert_respond_to obj, :empty?
  assert obj.empty?, msg
end
assert_equal(exp, act, msg = nil) click to toggle source

Fails unless exp == act printing the difference between the two, if possible.

If there is no visible difference but the assertion fails, you should suspect that your #== is buggy, or your inspect output is missing crucial details.

For floats use assert_in_delta.

See also: ::diff

# File lib/minitest/assertions.rb, line 161
def assert_equal exp, act, msg = nil
  msg = message(msg, E) { diff exp, act }
  assert exp == act, msg
end
assert_in_delta(exp, act, delta = 0.001, msg = nil) click to toggle source

For comparing Floats. Fails unless exp and act are within delta of each other.

assert_in_delta Math::PI, (22.0 / 7.0), 0.01
# File lib/minitest/assertions.rb, line 172
def assert_in_delta exp, act, delta = 0.001, msg = nil
  n = (exp - act).abs
  msg = message(msg) {
    "Expected |#{exp} - #{act}| (#{n}) to be <= #{delta}"
  }
  assert delta >= n, msg
end
assert_in_epsilon(a, b, epsilon = 0.001, msg = nil) click to toggle source

For comparing Floats. Fails unless exp and act have a relative error less than epsilon.

# File lib/minitest/assertions.rb, line 184
def assert_in_epsilon a, b, epsilon = 0.001, msg = nil
  assert_in_delta a, b, [a.abs, b.abs].min * epsilon, msg
end
assert_includes(collection, obj, msg = nil) click to toggle source

Fails unless collection includes obj.

# File lib/minitest/assertions.rb, line 191
def assert_includes collection, obj, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(collection)} to include #{mu_pp(obj)}"
  }
  assert_respond_to collection, :include?
  assert collection.include?(obj), msg
end
assert_instance_of(cls, obj, msg = nil) click to toggle source

Fails unless obj is an instance of cls.

# File lib/minitest/assertions.rb, line 202
def assert_instance_of cls, obj, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(obj)} to be an instance of #{cls}, not #{obj.class}"
  }

  assert obj.instance_of?(cls), msg
end
assert_kind_of(cls, obj, msg = nil) click to toggle source

Fails unless obj is a kind of cls.

# File lib/minitest/assertions.rb, line 213
def assert_kind_of cls, obj, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(obj)} to be a kind of #{cls}, not #{obj.class}" }

  assert obj.kind_of?(cls), msg
end
assert_match(matcher, obj, msg = nil) click to toggle source

Fails unless matcher =~ obj.

# File lib/minitest/assertions.rb, line 223
def assert_match matcher, obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp matcher} to match #{mu_pp obj}" }
  assert_respond_to matcher, :"=~"
  matcher = Regexp.new Regexp.escape matcher if String === matcher
  assert matcher =~ obj, msg
end
assert_nil(obj, msg = nil) click to toggle source

Fails unless obj is nil

# File lib/minitest/assertions.rb, line 233
def assert_nil obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp(obj)} to be nil" }
  assert obj.nil?, msg
end
assert_operator(o1, op, o2 = UNDEFINED, msg = nil) click to toggle source

For testing with binary operators. Eg:

assert_operator 5, :<=, 4
# File lib/minitest/assertions.rb, line 243
def assert_operator o1, op, o2 = UNDEFINED, msg = nil
  return assert_predicate o1, op, msg if UNDEFINED == o2
  msg = message(msg) { "Expected #{mu_pp(o1)} to be #{op} #{mu_pp(o2)}" }
  assert o1.__send__(op, o2), msg
end
assert_output(stdout = nil, stderr = nil) { || ... } click to toggle source

Fails if stdout or stderr do not output the expected results. Pass in nil if you don't care about that streams output. Pass in “” if you require it to be silent. Pass in a regexp if you want to pattern match.

NOTE: this uses capture_io, not capture_subprocess_io.

See also: assert_silent

# File lib/minitest/assertions.rb, line 259
def assert_output stdout = nil, stderr = nil
  out, err = capture_io do
    yield
  end

  err_msg = Regexp === stderr ? :assert_match : :assert_equal if stderr
  out_msg = Regexp === stdout ? :assert_match : :assert_equal if stdout

  y = send err_msg, stderr, err, "In stderr" if err_msg
  x = send out_msg, stdout, out, "In stdout" if out_msg

  (!stdout || x) && (!stderr || y)
end
assert_predicate(o1, op, msg = nil) click to toggle source

For testing with predicates. Eg:

assert_predicate str, :empty?

This is really meant for specs and is front-ended by #assert_operator:

str.must_be :empty?
# File lib/minitest/assertions.rb, line 282
def assert_predicate o1, op, msg = nil
  msg = message(msg) { "Expected #{mu_pp(o1)} to be #{op}" }
  assert o1.__send__(op), msg
end
assert_raises(*exp) { || ... } click to toggle source

Fails unless the block raises one of exp. Returns the exception matched so you can check the message, attributes, etc.

exp takes an optional message on the end to help explain failures and defaults to StandardError if no exception class is passed.

# File lib/minitest/assertions.rb, line 295
def assert_raises *exp
  msg = "#{exp.pop}.\n" if String === exp.last
  exp << StandardError if exp.empty?

  begin
    yield
  rescue *exp => e
    pass # count assertion
    return e
  rescue Minitest::Skip, Minitest::Assertion
    # don't count assertion
    raise
  rescue SignalException, SystemExit
    raise
  rescue Exception => e
    flunk proc {
      exception_details(e, "#{msg}#{mu_pp(exp)} exception expected, not")
    }
  end

  exp = exp.first if exp.size == 1

  flunk "#{msg}#{mu_pp(exp)} expected but nothing was raised."
end
assert_respond_to(obj, meth, msg = nil) click to toggle source

Fails unless obj responds to meth.

# File lib/minitest/assertions.rb, line 323
def assert_respond_to obj, meth, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(obj)} (#{obj.class}) to respond to ##{meth}"
  }
  assert obj.respond_to?(meth), msg
end
assert_same(exp, act, msg = nil) click to toggle source

Fails unless exp and act are equal?

# File lib/minitest/assertions.rb, line 333
def assert_same exp, act, msg = nil
  msg = message(msg) {
    data = [mu_pp(act), act.object_id, mu_pp(exp), exp.object_id]
    "Expected %s (oid=%d) to be the same as %s (oid=%d)" % data
  }
  assert exp.equal?(act), msg
end
assert_send(send_ary, m = nil) click to toggle source

send_ary is a receiver, message and arguments.

Fails unless the call returns a true value

# File lib/minitest/assertions.rb, line 346
def assert_send send_ary, m = nil
  recv, msg, *args = send_ary
  m = message(m) {
    "Expected #{mu_pp(recv)}.#{msg}(*#{mu_pp(args)}) to return true" }
  assert recv.__send__(msg, *args), m
end
assert_silent() { || ... } click to toggle source

Fails if the block outputs anything to stderr or stdout.

See also: assert_output

# File lib/minitest/assertions.rb, line 358
def assert_silent
  assert_output "", "" do
    yield
  end
end
assert_throws(sym, msg = nil) { || ... } click to toggle source

Fails unless the block throws sym

# File lib/minitest/assertions.rb, line 367
def assert_throws sym, msg = nil
  default = "Expected #{mu_pp(sym)} to have been thrown"
  caught = true
  catch(sym) do
    begin
      yield
    rescue ThreadError => e       # wtf?!? 1.8 + threads == suck
      default += ", not \:#{e.message[/uncaught throw \`(\w+?)\'/, 1]}"
    rescue ArgumentError => e     # 1.9 exception
      default += ", not #{e.message.split(/ /).last}"
    rescue NameError => e         # 1.8 exception
      default += ", not #{e.name.inspect}"
    end
    caught = false
  end

  assert caught, message(msg) { default }
end
capture_io() { || ... } click to toggle source

Captures $stdout and $stderr into strings:

out, err = capture_io do
  puts "Some info"
  warn "You did a bad thing"
end

assert_match %r%info%, out
assert_match %r%bad%, err

NOTE: For efficiency, this method uses StringIO and does not capture IO for subprocesses. Use capture_subprocess_io for that.

# File lib/minitest/assertions.rb, line 401
def capture_io
  _synchronize do
    begin
      captured_stdout, captured_stderr = StringIO.new, StringIO.new

      orig_stdout, orig_stderr = $stdout, $stderr
      $stdout, $stderr         = captured_stdout, captured_stderr

      yield

      return captured_stdout.string, captured_stderr.string
    ensure
      $stdout = orig_stdout
      $stderr = orig_stderr
    end
  end
end
capture_subprocess_io() { || ... } click to toggle source

Captures $stdout and $stderr into strings, using Tempfile to ensure that subprocess IO is captured as well.

out, err = capture_subprocess_io do
  system "echo Some info"
  system "echo You did a bad thing 1>&2"
end

assert_match %r%info%, out
assert_match %r%bad%, err

NOTE: This method is approximately 10x slower than capture_io so only use it when you need to test the output of a subprocess.

# File lib/minitest/assertions.rb, line 434
def capture_subprocess_io
  _synchronize do
    begin
      require "tempfile"

      captured_stdout, captured_stderr = Tempfile.new("out"), Tempfile.new("err")

      orig_stdout, orig_stderr = $stdout.dup, $stderr.dup
      $stdout.reopen captured_stdout
      $stderr.reopen captured_stderr

      yield

      $stdout.rewind
      $stderr.rewind

      return captured_stdout.read, captured_stderr.read
    ensure
      captured_stdout.unlink
      captured_stderr.unlink
      $stdout.reopen orig_stdout
      $stderr.reopen orig_stderr
    end
  end
end
diff(exp, act) click to toggle source

Returns a diff between exp and act. If there is no known diff command or if it doesn't make sense to diff the output (single line, short output), then it simply returns a basic comparison between the two.

# File lib/minitest/assertions.rb, line 57
def diff exp, act
  expect = mu_pp_for_diff exp
  butwas = mu_pp_for_diff act
  result = nil

  need_to_diff =
    (expect.include?("\n")    ||
     butwas.include?("\n")    ||
     expect.size > 30         ||
     butwas.size > 30         ||
     expect == butwas)        &&
    Minitest::Assertions.diff

  return "Expected: #{mu_pp exp}\n  Actual: #{mu_pp act}" unless
    need_to_diff

  Tempfile.open("expect") do |a|
    a.puts expect
    a.flush

    Tempfile.open("butwas") do |b|
      b.puts butwas
      b.flush

      result = %x`#{Minitest::Assertions.diff} #{a.path} #{b.path}`
      result.sub!(/^\-\-\- .+/, "--- expected")
      result.sub!(/^\+\+\+ .+/, "+++ actual")

      if result.empty? then
        klass = exp.class
        result = [
                  "No visible difference in the #{klass}#inspect output.\n",
                  "You should look at the implementation of #== on ",
                  "#{klass} or its members.\n",
                  expect,
                 ].join
      end
    end
  end

  result
end
exception_details(e, msg) click to toggle source

Returns details for exception e

# File lib/minitest/assertions.rb, line 463
def exception_details e, msg
  [
   "#{msg}",
   "Class: <#{e.class}>",
   "Message: <#{e.message.inspect}>",
   "---Backtrace---",
   "#{Minitest.filter_backtrace(e.backtrace).join("\n")}",
   "---------------",
  ].join "\n"
end
flunk(msg = nil) click to toggle source

Fails with msg

# File lib/minitest/assertions.rb, line 477
def flunk msg = nil
  msg ||= "Epic Fail!"
  assert false, msg
end
message(msg = nil, ending = nil, &default) click to toggle source

Returns a proc that will output msg along with the default message.

# File lib/minitest/assertions.rb, line 485
def message msg = nil, ending = nil, &default
  proc {
    msg = msg.call.chomp(".") if Proc === msg
    custom_message = "#{msg}.\n" unless msg.nil? or msg.to_s.empty?
    "#{custom_message}#{default.call}#{ending || "."}"
  }
end
mu_pp(obj) click to toggle source

This returns a human-readable version of obj. By default inspect is called. You can override this to use pretty_print if you want.

# File lib/minitest/assertions.rb, line 105
def mu_pp obj
  s = obj.inspect
  s = s.encode Encoding.default_external if defined? Encoding
  s
end
mu_pp_for_diff(obj) click to toggle source

This returns a diff-able human-readable version of obj. This differs from the regular #mu_pp because it expands escaped newlines and makes hex-values generic (like object_ids). This uses #mu_pp to do the first pass and then cleans it up.

# File lib/minitest/assertions.rb, line 117
def mu_pp_for_diff obj
  mu_pp(obj).gsub(/\n/, "\n").gsub(/:0x[a-fA-F0-9]{4,}/m, ":0xXXXXXX")
end
pass(_msg = nil) click to toggle source

used for counting assertions

# File lib/minitest/assertions.rb, line 496
def pass _msg = nil
  assert true
end
refute(test, msg = nil) click to toggle source

Fails if test is truthy.

# File lib/minitest/assertions.rb, line 503
def refute test, msg = nil
  msg ||= "Failed refutation, no message given"
  not assert !test, msg
end
refute_empty(obj, msg = nil) click to toggle source

Fails if obj is empty.

# File lib/minitest/assertions.rb, line 511
def refute_empty obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp(obj)} to not be empty" }
  assert_respond_to obj, :empty?
  refute obj.empty?, msg
end
refute_equal(exp, act, msg = nil) click to toggle source

Fails if exp == act.

For floats use refute_in_delta.

# File lib/minitest/assertions.rb, line 522
def refute_equal exp, act, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(act)} to not be equal to #{mu_pp(exp)}"
  }
  refute exp == act, msg
end
refute_in_delta(exp, act, delta = 0.001, msg = nil) click to toggle source

For comparing Floats. Fails if exp is within delta of act.

refute_in_delta Math::PI, (22.0 / 7.0)
# File lib/minitest/assertions.rb, line 534
def refute_in_delta exp, act, delta = 0.001, msg = nil
  n = (exp - act).abs
  msg = message(msg) {
    "Expected |#{exp} - #{act}| (#{n}) to not be <= #{delta}"
  }
  refute delta >= n, msg
end
refute_in_epsilon(a, b, epsilon = 0.001, msg = nil) click to toggle source

For comparing Floats. Fails if exp and act have a relative error less than epsilon.

# File lib/minitest/assertions.rb, line 546
def refute_in_epsilon a, b, epsilon = 0.001, msg = nil
  refute_in_delta a, b, a * epsilon, msg
end
refute_includes(collection, obj, msg = nil) click to toggle source

Fails if collection includes obj.

# File lib/minitest/assertions.rb, line 553
def refute_includes collection, obj, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(collection)} to not include #{mu_pp(obj)}"
  }
  assert_respond_to collection, :include?
  refute collection.include?(obj), msg
end
refute_instance_of(cls, obj, msg = nil) click to toggle source

Fails if obj is an instance of cls.

# File lib/minitest/assertions.rb, line 564
def refute_instance_of cls, obj, msg = nil
  msg = message(msg) {
    "Expected #{mu_pp(obj)} to not be an instance of #{cls}"
  }
  refute obj.instance_of?(cls), msg
end
refute_kind_of(cls, obj, msg = nil) click to toggle source

Fails if obj is a kind of cls.

# File lib/minitest/assertions.rb, line 574
def refute_kind_of cls, obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp(obj)} to not be a kind of #{cls}" }
  refute obj.kind_of?(cls), msg
end
refute_match(matcher, obj, msg = nil) click to toggle source

Fails if matcher =~ obj.

# File lib/minitest/assertions.rb, line 582
def refute_match matcher, obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp matcher} to not match #{mu_pp obj}" }
  assert_respond_to matcher, :"=~"
  matcher = Regexp.new Regexp.escape matcher if String === matcher
  refute matcher =~ obj, msg
end
refute_nil(obj, msg = nil) click to toggle source

Fails if obj is nil.

# File lib/minitest/assertions.rb, line 592
def refute_nil obj, msg = nil
  msg = message(msg) { "Expected #{mu_pp(obj)} to not be nil" }
  refute obj.nil?, msg
end
refute_operator(o1, op, o2 = UNDEFINED, msg = nil) click to toggle source

Fails if o1 is not op o2. Eg:

refute_operator 1, :>, 2 #=> pass
refute_operator 1, :<, 2 #=> fail
# File lib/minitest/assertions.rb, line 603
def refute_operator o1, op, o2 = UNDEFINED, msg = nil
  return refute_predicate o1, op, msg if UNDEFINED == o2
  msg = message(msg) { "Expected #{mu_pp(o1)} to not be #{op} #{mu_pp(o2)}" }
  refute o1.__send__(op, o2), msg
end
refute_predicate(o1, op, msg = nil) click to toggle source

For testing with predicates.

refute_predicate str, :empty?

This is really meant for specs and is front-ended by #refute_operator:

str.wont_be :empty?
# File lib/minitest/assertions.rb, line 618
def refute_predicate o1, op, msg = nil
  msg = message(msg) { "Expected #{mu_pp(o1)} to not be #{op}" }
  refute o1.__send__(op), msg
end
refute_respond_to(obj, meth, msg = nil) click to toggle source

Fails if obj responds to the message meth.

# File lib/minitest/assertions.rb, line 626
def refute_respond_to obj, meth, msg = nil
  msg = message(msg) { "Expected #{mu_pp(obj)} to not respond to #{meth}" }

  refute obj.respond_to?(meth), msg
end
refute_same(exp, act, msg = nil) click to toggle source

Fails if exp is the same (by object identity) as act.

# File lib/minitest/assertions.rb, line 635
def refute_same exp, act, msg = nil
  msg = message(msg) {
    data = [mu_pp(act), act.object_id, mu_pp(exp), exp.object_id]
    "Expected %s (oid=%d) to not be the same as %s (oid=%d)" % data
  }
  refute exp.equal?(act), msg
end
skip(msg = nil, bt = caller) click to toggle source

Skips the current run. If run in verbose-mode, the skipped run gets listed at the end of the run but doesn't cause a failure exit code.

# File lib/minitest/assertions.rb, line 648
def skip msg = nil, bt = caller
  msg ||= "Skipped, no message given"
  @skip = true
  raise Minitest::Skip, msg, bt
end
skipped?() click to toggle source

Was this testcase skipped? Meant for teardown.

# File lib/minitest/assertions.rb, line 657
def skipped?
  defined?(@skip) and @skip
end