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
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 return @diff if defined? @diff @diff = if (RbConfig::CONFIG["host_os"] =~ /mswin|mingw/ and system "diff.exe", __FILE__, __FILE__) then "diff.exe -u" elsif system "gdiff", __FILE__, __FILE__ then "gdiff -u" # solaris and kin suck elsif system "diff", __FILE__, __FILE__ then "diff -u" else nil end end
Set the diff command to use in diff
.
# File lib/minitest/assertions.rb, line 45 def self.diff= o @diff = o end
Public Instance Methods
Fails unless test
is truthy.
# File lib/minitest/assertions.rb, line 171 def assert test, msg = nil self.assertions += 1 unless test then msg ||= "Expected #{mu_pp test} to be truthy." msg = msg.call if Proc === msg raise Minitest::Assertion, msg end true end
Fails unless obj
is empty.
# File lib/minitest/assertions.rb, line 188 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
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 nicer structural diffing, set Minitest::Test.make_my_diffs_pretty!
For floats use assert_in_delta.
See also: Minitest::Assertions.diff
# File lib/minitest/assertions.rb, line 214 def assert_equal exp, act, msg = nil msg = message(msg, E) { diff exp, act } result = assert exp == act, msg if nil == exp then if Minitest::VERSION >= "6" then refute_nil exp, "Use assert_nil if expecting nil." else warn "DEPRECATED: Use assert_nil if expecting nil from #{_where}. This will fail in Minitest 6." end end result end
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 235 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
For comparing Floats. Fails unless exp
and act
have a relative error less than epsilon
.
# File lib/minitest/assertions.rb, line 247 def assert_in_epsilon exp, act, epsilon = 0.001, msg = nil assert_in_delta exp, act, [exp.abs, act.abs].min * epsilon, msg end
Fails unless collection
includes obj
.
# File lib/minitest/assertions.rb, line 254 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
Fails unless obj
is an instance of cls
.
# File lib/minitest/assertions.rb, line 265 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
Fails unless obj
is a kind of cls
.
# File lib/minitest/assertions.rb, line 276 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
Fails unless matcher
=~
obj
.
# File lib/minitest/assertions.rb, line 287 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 Regexp.last_match end
Assert that the mock verifies correctly.
# File lib/minitest/mock.rb, line 250 def assert_mock mock assert mock.verify end
Fails unless obj
is nil
# File lib/minitest/assertions.rb, line 299 def assert_nil obj, msg = nil msg = message(msg) { "Expected #{mu_pp obj} to be nil" } assert obj.nil?, msg end
For testing with binary operators. Eg:
assert_operator 5, :<=, 4
# File lib/minitest/assertions.rb, line 309 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
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.
assert_output(/hey/) { method_with_output }
NOTE: this uses capture_io
, not capture_subprocess_io
.
See also: assert_silent
# File lib/minitest/assertions.rb, line 327 def assert_output stdout = nil, stderr = nil flunk "assert_output requires a block to capture output." unless block_given? 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) rescue Assertion raise rescue => e raise UnexpectedError, e end
Fails unless path
exists.
# File lib/minitest/assertions.rb, line 351 def assert_path_exists path, msg = nil msg = message(msg) { "Expected path '#{path}' to exist" } assert File.exist?(path), msg end
For testing with pattern matching (only supported with Ruby 3.0 and later)
# pass assert_pattern { [1,2,3] => [Integer, Integer, Integer] } # fail "length mismatch (given 3, expected 1)" assert_pattern { [1,2,3] => [Integer] }
The bare =>
pattern will raise a NoMatchingPatternError on failure, which would normally be counted as a test error. This assertion rescues NoMatchingPatternError and generates a test failure. Any other exception will be raised as normal and generate a test error.
# File lib/minitest/assertions.rb, line 370 def assert_pattern raise NotImplementedError, "only available in Ruby 3.0+" unless RUBY_VERSION >= "3.0" flunk "assert_pattern requires a block to capture errors." unless block_given? begin # TODO: remove after ruby 2.6 dropped yield pass rescue NoMatchingPatternError => e flunk e.message end end
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 391 def assert_predicate o1, op, msg = nil msg = message(msg) { "Expected #{mu_pp o1} to be #{op}" } assert o1.__send__(op), msg end
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. Eg:
assert_raises(CustomError) { method_with_custom_error }
With custom error message:
assert_raises(CustomError, 'This should have raised CustomError') { method_with_custom_error }
Using the returned object:
error = assert_raises(CustomError) do raise CustomError, 'This is really bad' end assert_equal 'This is really bad', error.message
# File lib/minitest/assertions.rb, line 418 def assert_raises *exp flunk "assert_raises requires a block to capture errors." unless block_given? 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::Assertion # incl Skip & UnexpectedError # 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
Fails unless obj
responds to meth
. include_all defaults to false to match Object#respond_to?
# File lib/minitest/assertions.rb, line 450 def assert_respond_to obj, meth, msg = nil, include_all: false msg = message(msg) { "Expected #{mu_pp obj} (#{obj.class}) to respond to ##{meth}" } assert obj.respond_to?(meth, include_all), msg end
Fails unless exp
and act
are equal?
# File lib/minitest/assertions.rb, line 460 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
send_ary
is a receiver, message and arguments.
Fails unless the call returns a true value
# File lib/minitest/assertions.rb, line 473 def assert_send send_ary, m = nil warn "DEPRECATED: assert_send. From #{_where}" 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
Fails if the block outputs anything to stderr or stdout.
See also: assert_output
# File lib/minitest/assertions.rb, line 488 def assert_silent assert_output "", "" do yield end end
Fails unless the block throws sym
# File lib/minitest/assertions.rb, line 497 def assert_throws sym, msg = nil default = "Expected #{mu_pp sym} to have been thrown" caught = true value = 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 raise e unless e.message.include? "uncaught throw" default += ", not #{e.message.split(/ /).last}" rescue NameError => e # 1.8 exception raise e unless e.name == sym default += ", not #{e.name.inspect}" end caught = false end assert caught, message(msg) { default } value rescue Assertion raise rescue => e raise UnexpectedError, e end
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 538 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
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 571 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 $stdout.reopen orig_stdout $stderr.reopen orig_stderr orig_stdout.close orig_stderr.close captured_stdout.close! captured_stderr.close! end end end
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.
See things_to_diff
for more info.
# File lib/minitest/assertions.rb, line 57 def diff exp, act result = nil expect, butwas = things_to_diff exp, act return "Expected: #{mu_pp exp}\n Actual: #{mu_pp act}" unless expect 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
Returns details for exception e
# File lib/minitest/assertions.rb, line 603 def exception_details e, msg [ msg, "Class: <#{e.class}>", "Message: <#{e.message.inspect}>", "---Backtrace---", Minitest.filter_backtrace(e.backtrace), "---------------", ].join "\n" end
Fails after a given date (in the local time zone). This allows you to put time-bombs in your tests if you need to keep something around until a later date lest you forget about it.
# File lib/minitest/assertions.rb, line 619 def fail_after y, m, d, msg flunk msg if Time.now > Time.local(y, m, d) end
Fails with msg
.
# File lib/minitest/assertions.rb, line 626 def flunk msg = nil msg ||= "Epic Fail!" assert false, msg end
Returns a proc that will output msg
along with the default message.
# File lib/minitest/assertions.rb, line 634 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
This returns a human-readable version of obj
. By default inspect is called. You can override this to use pretty_inspect if you want.
See Minitest::Test.make_my_diffs_pretty!
# File lib/minitest/assertions.rb, line 127 def mu_pp obj s = obj.inspect.encode Encoding.default_external return s unless String === obj && (obj.encoding != Encoding.default_external || !obj.valid_encoding?) enc = "# encoding: #{obj.encoding}" val = "# valid: #{obj.valid_encoding?}" [enc, val, s].join "\n" end
This returns a diff-able more human-readable version of obj
. This differs from the regular mu_pp
because it expands escaped newlines and makes hex-values (like object_ids) generic. This uses mu_pp
to do the first pass and then cleans it up.
# File lib/minitest/assertions.rb, line 145 def mu_pp_for_diff obj str = mu_pp obj # both '\n' & '\\n' (_after_ mu_pp (aka inspect)) single = str.match?(/(?<!\\|^)\\n/) double = str.match?(/(?<=\\|^)\\n/) process = if single ^ double then if single then lambda { |s| s == "\\n" ? "\n" : s } # unescape else lambda { |s| s == "\\\\n" ? "\\n\n" : s } # unescape a bit, add nls end else :itself # leave it alone end str .gsub(/\\?\\n/, &process) .gsub(/:0x[a-fA-F0-9]{4,}/m, ":0xXXXXXX") # anonymize hex values end
used for counting assertions
# File lib/minitest/assertions.rb, line 645 def pass _msg = nil assert true end
Fails if test
is truthy.
# File lib/minitest/assertions.rb, line 652 def refute test, msg = nil msg ||= message { "Expected #{mu_pp test} to not be truthy" } assert !test, msg end
Fails if obj
is empty.
# File lib/minitest/assertions.rb, line 660 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
Fails if exp == act
.
For floats use refute_in_delta.
# File lib/minitest/assertions.rb, line 671 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
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 683 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
For comparing Floats. Fails if exp
and act
have a relative error less than epsilon
.
# File lib/minitest/assertions.rb, line 695 def refute_in_epsilon a, b, epsilon = 0.001, msg = nil refute_in_delta a, b, a * epsilon, msg end
Fails if collection
includes obj
.
# File lib/minitest/assertions.rb, line 702 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
Fails if obj
is an instance of cls
.
# File lib/minitest/assertions.rb, line 713 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
Fails if obj
is a kind of cls
.
# File lib/minitest/assertions.rb, line 723 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
Fails if matcher
=~
obj
.
# File lib/minitest/assertions.rb, line 731 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
Fails if obj
is nil.
# File lib/minitest/assertions.rb, line 741 def refute_nil obj, msg = nil msg = message(msg) { "Expected #{mu_pp obj} to not be nil" } refute obj.nil?, msg end
Fails if o1
is not op
o2
. Eg:
refute_operator 1, :>, 2 #=> pass refute_operator 1, :<, 2 #=> fail
# File lib/minitest/assertions.rb, line 776 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
Fails if path
exists.
# File lib/minitest/assertions.rb, line 785 def refute_path_exists path, msg = nil msg = message(msg) { "Expected path '#{path}' to not exist" } refute File.exist?(path), msg end
For testing with pattern matching (only supported with Ruby 3.0 and later)
# pass refute_pattern { [1,2,3] => [String] } # fail "NoMatchingPatternError expected, but nothing was raised." refute_pattern { [1,2,3] => [Integer, Integer, Integer] }
This assertion expects a NoMatchingPatternError exception, and will fail if none is raised. Any other exceptions will be raised as normal and generate a test error.
# File lib/minitest/assertions.rb, line 758 def refute_pattern raise NotImplementedError, "only available in Ruby 3.0+" unless RUBY_VERSION >= "3.0" flunk "refute_pattern requires a block to capture errors." unless block_given? begin yield flunk "NoMatchingPatternError expected, but nothing was raised." rescue NoMatchingPatternError pass end end
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 799 def refute_predicate o1, op, msg = nil msg = message(msg) { "Expected #{mu_pp o1} to not be #{op}" } refute o1.__send__(op), msg end
Fails if obj
responds to the message meth
. include_all defaults to false to match Object#respond_to?
# File lib/minitest/assertions.rb, line 808 def refute_respond_to obj, meth, msg = nil, include_all: false msg = message(msg) { "Expected #{mu_pp obj} to not respond to #{meth}" } refute obj.respond_to?(meth, include_all), msg end
Fails if exp
is the same (by object identity) as act
.
# File lib/minitest/assertions.rb, line 817 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
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 830 def skip msg = nil, _ignored = nil msg ||= "Skipped, no message given" @skip = true raise Minitest::Skip, msg end
Skips the current run until a given date (in the local time zone). This allows you to put some fixes on hold until a later date, but still holds you accountable and prevents you from forgetting it.
# File lib/minitest/assertions.rb, line 842 def skip_until y, m, d, msg skip msg if Time.now < Time.local(y, m, d) where = caller(1..1).first.rpartition(":in").reject(&:empty?).first warn "Stale skip_until %p at %s" % [msg, where] end
Was this testcase skipped? Meant for teardown.
# File lib/minitest/assertions.rb, line 851 def skipped? defined?(@skip) and @skip end
Returns things to diff [expect, butwas], or [nil, nil] if nothing to diff.
Criterion:
-
Strings include newlines or escaped newlines, but not both.
-
or: String lengths are > 30 characters.
-
or: Strings are equal to each other (but maybe different encodings?).
-
and: we found a diff executable.
# File lib/minitest/assertions.rb, line 102 def things_to_diff exp, act expect = mu_pp_for_diff exp butwas = mu_pp_for_diff act e1, e2 = expect.include?("\n"), expect.include?("\\n") b1, b2 = butwas.include?("\n"), butwas.include?("\\n") need_to_diff = (e1 ^ e2 || b1 ^ b2 || expect.size > 30 || butwas.size > 30 || expect == butwas) && Minitest::Assertions.diff need_to_diff && [expect, butwas] end