Custom assertion message for unit tests


#1

I’m having trouble trying to figure out how to customize an assertion
message when running unit tests. In particular, I want to check the
permissions on a file, so I have something like:

assert_equal(0755, File.stat(test_file).mode & 0777)

If it fails, I get a message like:

<493> expected but was
<420>.

and of course I would like the expected and actual permissions to be
displayed in octal rather than decimal. How can I do that?


#2

On Feb 4, 2009, at 5:59 PM, Will P. wrote:

and of course I would like the expected and actual permissions to be
displayed in octal rather than decimal. How can I do that?


Will

Perhaps something like:

$ ruby -r’test/unit’
class SomeTest < Test::Unit::TestCase
def setup
@test_file = ‘some_file’
File.open(@test_file, ‘w’) {|f| f.write “Hello!”}
end
def test_bad_file_mode
File.chmod(0644, @test_file)

 assert_equal '0755', '%#o'%[File.stat(@test_file).mode & 0777],

“Mode of #{@test_file}”
end

def test_good_file_mode
File.chmod(0755, @test_file)

 assert_equal '0755', '%#o'%[File.stat(@test_file).mode & 0777],

“Mode of #{@test_file}”
end
end
END
Loaded suite -
Started
F.
Finished in 0.025823 seconds.

  1. Failure:
    test_bad_file_mode(SomeTest) [-:9]:
    Mode of some_file.
    <“0755”> expected but was
    <“0644”>.

2 tests, 2 assertions, 1 failures, 0 errors

Note that I’m doing the conversion to octal myself with the ‘%#o’ and
String#%

It would be better to pull this into a helper method:

$ ruby -r’test/unit’
class SomeTest < Test::Unit::TestCase
def assert_mode(expected_mode, actual_mode, message=nil)
assert_equal ‘%#o’%expected_mode, ‘%#o’%actual_mode, message
end

def setup
@test_file = ‘some_file’
File.open(@test_file, ‘w’) {|f| f.write “Hello!”}
end
def test_bad_file_mode
File.chmod(0644, @test_file)

 assert_mode 0755, File.stat(@test_file).mode & 0777, "Mode of

#{@test_file}"
end

def test_good_file_mode
File.chmod(0755, @test_file)

 assert_mode 0755, File.stat(@test_file).mode & 0777, "Mode of

#{@test_file}"
end
end
END
Loaded suite -
Started
F.
Finished in 0.0107 seconds.

  1. Failure:
    test_bad_file_mode(SomeTest)
    [-:3:in assert_mode' -:13:intest_bad_file_mode’]:
    Mode of some_file.
    <“0755”> expected but was
    <“0644”>.

2 tests, 2 assertions, 1 failures, 0 errors

Do you really want
assert File.stat(@test_file).executable?
instead of a specific mode?

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid


#3

Will P. wrote:

and of course I would like the expected and actual permissions to be
displayed in octal rather than decimal. How can I do that?

(Unless if you use Ruby 1.8.7), install gem assert2, then write:

assert{ ‘755’ == (File.stat(test_file).mode & 0777).to_s(8) }

When that fails, it prints out every expression, with its intermediate
value,
including those bitfields’ decimal representations, and

  1. Failure:
    test_assert_classic_message(Assert21Suite)
    [/cygdrive/c/Users/Phlip/.UNA/2/1/1/assert2/lib/assert2.rb:214:in
    assert_' /cygdrive/c/Users/Phlip/.UNA/2/1/1/assert2/lib/assert2.rb:76:inassert’
    test/assert2_suite.rb:403:in `test_assert_classic_message’]:

assert{ “755” == ( File.stat(test_file).mode() & 511 ).to_s(8) }
–> false - should pass
test_file -->
“test/assert2_suite.rb”
File.stat(test_file) --> #<File::Stat***
File.stat(test_file).mode() --> 33216
( File.stat(test_file).mode() & 511 ) --> 448
( File.stat(test_file).mode() & 511 ).to_s(8) --> “700”.

29 tests, 115 assertions, 1 failures, 0 errors

All assertions should reflect everything they possibly can at failure
time,
without too much excess verbiage when you write them. They should be
easy to
write and comprehensive when they fail. Assert{ 2.0 } maximizes your
bang-buck
ratio there!


#4

Rob B. wrote:

<493> expected but was
@test_file = ‘some_file’
File.chmod(0755, @test_file)

  1. Failure:
    test_bad_file_mode(SomeTest) [-:9]:
    Mode of some_file.
    <“0755”> expected but was
    <“0644”>.

2 tests, 2 assertions, 1 failures, 0 errors

This is certainly an improvement on my version, but it is not completely
satisfying - the reason being that by explicitly converting the
permissions
to a string they get displayed as strings, i.e., I would like to see:

<755> expected

rather than:

<“0755”> expected

F.
2 tests, 2 assertions, 1 failures, 0 errors
I’m not sure I understand this - what’s the advantage of defining the
assert_mode method over using the already defined methods?

Do you really want
assert File.stat(@test_file).executable?
instead of a specific mode?

Yes, because I want also to check for being read-only in addition to
being
executable in the file permissions.


#5

On Feb 4, 2009, at 8:39 PM, Will P. wrote:

If it fails, I get a message like:

<493> expected but was
<420>.

and of course I would like the expected and actual permissions to be
displayed in octal rather than decimal. How can I do that?

Perhaps something like:

completely

Note that I’m doing the conversion to octal myself with the ‘%#o’ and
def setup
def test_good_file_mode
Finished in 0.0107 seconds.

I’m not sure I understand this - what’s the advantage of defining the
assert_mode method over using the already defined methods?

Look at the resulting test and it’s failure message:
assert_mode 0755, File.stat(@test_file).mode & 0777

<“0755”> expected but was
<“0644”>.

Compared to what you had to start:
assert_equal(0755, File.stat(test_file).mode & 0777)

<493> expected but was
<420>.

Pretty close, no?

Do you really want
assert File.stat(@test_file).executable?
instead of a specific mode?

Yes, because I want also to check for being read-only in addition to
being
executable in the file permissions.


Will

But you could go all the way with:

$ cat ml_mode_test.rb
require ‘test/unit’

module Test
module Unit
module Assertions
##
# Asserts that the octal modes are equal.
# If given a +:mask+ option, will only compare those bits.
#
# Example:
# assert_mode 0444, File.stat(name).mode, “Always
readable”, :mask => 0777
#
def assert_mode(expected_mode, actual_mode,
options_or_message=nil, options=nil)
if options.nil? && Hash === options_or_message
message, options = nil, options_or_message
elsif
message = options_or_message
end
full_message = message ? message.chomp+"\n" : ‘’
full_message << “<%#o> expected but was\n<%#o>”%
[expected_mode, actual_mode]
if Hash === options && options.has_key?(:mask)
mask = options[:mask]
expected_mode &= mask
actual_mode &= mask
full_message << " (applying %#o mask)"%mask
end
assert_block(full_message) { expected_mode == actual_mode }
end
end
end
end

class SomeTest < Test::Unit::TestCase

def setup
@test_file = ‘some_file’
File.open(@test_file, ‘w’) {|f| f.write “Hello!”}
File.chmod(0644, @test_file)
end

def test_with_equal
assert_equal 0755, File.stat(@test_file).mode & 0777
end

def test_with_equal_and_message
assert_equal 0755, File.stat(@test_file).mode & 0777, “equal?”
end

def test_with_mode
assert_mode 0755, File.stat(@test_file).mode & 0777
end

def test_with_mode_and_mask
assert_mode 0755, File.stat(@test_file).mode, :mask => 0777
end

def test_with_mode_and_message
assert_mode 0755, File.stat(@test_file).mode & 0777, “executable?”
end

def test_with_mode_big_finish
assert_mode 0755, File.stat(@test_file).mode,
“executable?”, :mask => 0777
end

end
END
rab:code/ruby $ ruby ml_mode_test.rb
Loaded suite ml_mode_test
Started
FFFFFF
Finished in 0.074508 seconds.

  1. Failure:
    test_with_equal(SomeTest) [ml_mode_test.rb:42]:
    <493> expected but was
    <420>.

  2. Failure:
    test_with_equal_and_message(SomeTest) [ml_mode_test.rb:46]:
    equal?.
    <493> expected but was
    <420>.

  3. Failure:
    test_with_mode(SomeTest)
    [ml_mode_test.rb:27:in assert_mode' ml_mode_test.rb:50:intest_with_mode’]:
    <0755> expected but was
    <0644>

  4. Failure:
    test_with_mode_and_mask(SomeTest)
    [ml_mode_test.rb:27:in assert_mode' ml_mode_test.rb:54:intest_with_mode_and_mask’]:
    <0755> expected but was
    <0100644> (applying 0777 mask)

  5. Failure:
    test_with_mode_and_message(SomeTest)
    [ml_mode_test.rb:27:in assert_mode' ml_mode_test.rb:58:intest_with_mode_and_message’]:
    executable?
    <0755> expected but was
    <0644>

  6. Failure:
    test_with_mode_big_finish(SomeTest)
    [ml_mode_test.rb:27:in assert_mode' ml_mode_test.rb:62:intest_with_mode_big_finish’]:
    executable?
    <0755> expected but was
    <0100644> (applying 0777 mask)

6 tests, 6 assertions, 6 failures, 0 errors

It just depends on how far you want to take it.

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid


#6

Maybe it is not necessary to customize the assertion so much.

On 04.02.2009, at 23:59, Will P. wrote:

I would like the expected and actual permissions to be
displayed in octal rather than decimal. How can I do that?

irb(main):005:0> “420”.to_i
=> 420
irb(main):006:0> “420”.to_i.to_s(8)
=> “644”
irb(main):007:0> “420”.to_i.to_s(8).to_i
=> 644

regards, Sandor
Szücs


#7

Will P. wrote:

Yes, because I want also to check for being read-only in addition to being
executable in the file permissions.

If I felt the request to take the “” off of “0775” sounded a little
petty, this
would probably be on account of I’m disturbed by so much effort to
achieve 0775
when “File(…).readonly? == true” is a little bit more readable!

How about assert{ ls -l #{filename.inspect} =~ /-rwxr-wr-w/ } ?


#8

Sandor Szücs wrote:

=> “644”
irb(main):007:0> “420”.to_i.to_s(8).to_i
=> 644

Tricky, but it works!


#9

On Wed, 04 Feb 2009 22:55:46 +0000, Will P. wrote:

and of course I would like the expected and actual permissions to be
displayed in octal rather than decimal. How can I do that?

All of the standard test/unit assertions let you pass a message to be
printed to explain the error, which will print in addition to the
automatic message. So store the mode in a local variable so you can use
it in both places.

acutalmode=File.stat(test_file).mode & 0777
assert_equal 0755, actualmode, “#{test_file} should have mode 755, but
has mode %o instead.” % [actualmode]

Or to supress the automatic message altogether and only print your
custom
message:

acutalmode=File.stat(test_file).mode & 0777
assert_block ("#{test_file} should have mode 755,
but has mode %o instead." % [actualmode]) {0755 == actualmode}

–Ken


#10

Ken B. wrote:

<493> expected but was
acutalmode=File.stat(test_file).mode & 0777
assert_equal 0755, actualmode, “#{test_file} should have mode 755, but
has mode %o instead.” % [actualmode]

Or to supress the automatic message altogether and only print your custom
message:

acutalmode=File.stat(test_file).mode & 0777
assert_block ("#{test_file} should have mode 755,
but has mode %o instead." % [actualmode]) {0755 == actualmode}

Thanks! This is just what I was looking for.