Module: Minitest::Assertions

Included in:
Test
Defined in:
lib/minitest/assertions.rb

Overview

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.

Constant Summary collapse

UNDEFINED =

:nodoc:

Object.new
E =

:nodoc:

""

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.diffObject

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



27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
# 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) ⇒ Object

Set the diff command to use in #diff.



47
48
49
# File 'lib/minitest/assertions.rb', line 47

def self.diff= o
  @diff = o
end

Instance Method Details

#_synchronizeObject

:nodoc:



134
135
136
# File 'lib/minitest/assertions.rb', line 134

def _synchronize # :nodoc:
  yield
end

#assert(test, msg = nil) ⇒ Object

Fails unless test is truthy.



124
125
126
127
128
129
130
131
132
# 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) ⇒ Object

Fails unless obj is empty.



141
142
143
144
145
# 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) ⇒ Object

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: Minitest::Assertions.diff



161
162
163
164
# 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) ⇒ Object

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


172
173
174
175
176
177
178
# 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) ⇒ Object

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



184
185
186
# 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) ⇒ Object

Fails unless collection includes obj.



191
192
193
194
195
196
197
# 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) ⇒ Object

Fails unless obj is an instance of cls.



202
203
204
205
206
207
208
# 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) ⇒ Object

Fails unless obj is a kind of cls.



213
214
215
216
217
218
# 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) ⇒ Object

Fails unless matcher =~ obj.



223
224
225
226
227
228
# 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) ⇒ Object

Fails unless obj is nil



233
234
235
236
# 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) ⇒ Object

For testing with binary operators. Eg:

assert_operator 5, :<=, 4


243
244
245
246
247
# 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) ⇒ Object

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



259
260
261
262
263
264
265
266
267
268
269
270
271
# 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) ⇒ Object

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?


282
283
284
285
# 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) ⇒ Object

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.



295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
# 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
    # 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) ⇒ Object

Fails unless obj responds to meth.



323
324
325
326
327
328
# 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) ⇒ Object

Fails unless exp and act are #equal?



333
334
335
336
337
338
339
# 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) ⇒ Object

send_ary is a receiver, message and arguments.

Fails unless the call returns a true value



346
347
348
349
350
351
# 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_silentObject

Fails if the block outputs anything to stderr or stdout.

See also: #assert_output



358
359
360
361
362
# File 'lib/minitest/assertions.rb', line 358

def assert_silent
  assert_output "", "" do
    yield
  end
end

#assert_throws(sym, msg = nil) ⇒ Object

Fails unless the block throws sym



367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
# 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_ioObject

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.



401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
# 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_ioObject

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.



434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
# 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) ⇒ Object

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.



57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
# 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 = `#{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) ⇒ Object

Returns details for exception e



463
464
465
466
467
468
469
470
471
472
# 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) ⇒ Object

Fails with msg



477
478
479
480
# File 'lib/minitest/assertions.rb', line 477

def flunk msg = nil
  msg ||= "Epic Fail!"
  assert false, msg
end

#message(msg = nil, ending = nil, &default) ⇒ Object

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



485
486
487
488
489
490
491
# 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) ⇒ Object

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



105
106
107
108
109
# 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) ⇒ Object

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.



117
118
119
# 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) ⇒ Object

used for counting assertions



496
497
498
# File 'lib/minitest/assertions.rb', line 496

def pass _msg = nil
  assert true
end

#refute(test, msg = nil) ⇒ Object

Fails if test is truthy.



503
504
505
506
# 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) ⇒ Object

Fails if obj is empty.



511
512
513
514
515
# 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) ⇒ Object

Fails if exp == act.

For floats use refute_in_delta.



522
523
524
525
526
527
# 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) ⇒ Object

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

refute_in_delta Math::PI, (22.0 / 7.0)


534
535
536
537
538
539
540
# 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) ⇒ Object

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



546
547
548
# 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) ⇒ Object

Fails if collection includes obj.



553
554
555
556
557
558
559
# 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) ⇒ Object

Fails if obj is an instance of cls.



564
565
566
567
568
569
# 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) ⇒ Object

Fails if obj is a kind of cls.



574
575
576
577
# 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) ⇒ Object

Fails if matcher =~ obj.



582
583
584
585
586
587
# 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) ⇒ Object

Fails if obj is nil.



592
593
594
595
# 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) ⇒ Object

Fails if o1 is not op o2. Eg:

refute_operator 1, :>, 2 #=> pass
refute_operator 1, :<, 2 #=> fail


603
604
605
606
607
# 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) ⇒ Object

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?


618
619
620
621
# 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) ⇒ Object

Fails if obj responds to the message meth.



626
627
628
629
630
# 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) ⇒ Object

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



635
636
637
638
639
640
641
# 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) ⇒ Object

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.

Raises:



648
649
650
651
652
# 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?Boolean

Was this testcase skipped? Meant for #teardown.

Returns:

  • (Boolean)


657
658
659
# File 'lib/minitest/assertions.rb', line 657

def skipped?
  defined?(@skip) and @skip
end