bats-assert
is a helper library providing common assertions for Bats.
In the context of this project, an assertion is a function that perform a test and returns 1
on failure or 0
on success.
To make debugging easier, the assertion also outputs relevant information on failure.
The output is formatted for readability.
To make assertions usable outside of @test
blocks, the output is sent to stderr.
The most recent invocation of Bats' run
function is used for testing assertions on output and status code.
This project has one dependency, for output formatting: bats-support
Read the shared documentation to learn how to install and load both libraries.
This project provides the following functions:
true
or false
.0
or 1
.These commands are described in more detail below.
For functions that have options, --
disables option parsing for the remaining arguments to allow using arguments identical to one of the allowed options.
assert_output -- '-p'
Specifying --
as an argument is similarly simple.
refute_line -- '--'
assert
Fail if the given expression evaluates to false.
Note: The expression must be a simple command. Compound commands, such as
[[
, can be used only when executed withbash -c
.
@test 'assert()' {
assert [ 1 -lt 0 ]
}
On failure, the failed expression is displayed.
-- assertion failed --
expression : [ 1 -lt 0 ]
--
refute
Fail if the given expression evaluates to true.
Note The expression must be a simple command. Compound commands, such as
[[
, can be used only when executed withbash -c
.
@test 'refute()' {
refute [ 1 -gt 0 ]
}
On failure, the successful expression is displayed.
-- assertion succeeded, but it was expected to fail --
expression : [ 1 -gt 0 ]
--
assert_equal
Fail if the two parameters, actual and expected value respectively, do not equal.
@test 'assert_equal()' {
assert_equal 'have' 'want'
}
On failure, the expected and actual values are displayed.
-- values do not equal --
expected : want
actual : have
--
If either value is longer than one line both are displayed in multi-line format.
assert_not_equal
Fail if the two parameters, actual and unexpected value respectively, are equal.
@test 'assert_not_equal()' {
assert_not_equal 'foobar' 'foobar'
}
On failure, the expected and actual values are displayed.
-- values should not be equal --
unexpected : foobar
actual : foobar
--
If either value is longer than one line both are displayed in multi-line format.
assert_success
Fail if $status
is not 0.
@test 'assert_success() status only' {
run bash -c "echo 'Error!'; exit 1"
assert_success
}
On failure, $status
and $output
are displayed.
-- command failed --
status : 1
output : Error!
--
If $output
is longer than one line, it is displayed in multi-line format.
assert_failure
Fail if $status
is 0.
@test 'assert_failure() status only' {
run echo 'Success!'
assert_failure
}
On failure, $output
is displayed.
-- command succeeded, but it was expected to fail --
output : Success!
--
If $output
is longer than one line, it is displayed in multi-line format.
When one parameter is specified, fail if $status
does not equal the expected status specified by the parameter.
@test 'assert_failure() with expected status' {
run bash -c "echo 'Error!'; exit 1"
assert_failure 2
}
On failure, the expected and actual status, and $output
are displayed.
-- command failed as expected, but status differs --
expected : 2
actual : 1
output : Error!
--
If $output
is longer than one line, it is displayed in multi-line format.
assert_output
This function helps to verify that a command or function produces the correct output by checking that the specified expected output matches the actual output.
Matching can be literal (default), partial or regular expression.
This function is the logical complement of refute_output
.
By default, literal matching is performed.
The assertion fails if $output
does not equal the expected output.
@test 'assert_output()' {
run echo 'have'
assert_output 'want'
}
On failure, the expected and actual output are displayed.
-- output differs --
expected : want
actual : have
--
If either value is longer than one line both are displayed in multi-line format.
To assert that any (non-empty) output exists at all, simply omit the matching argument.
@test 'assert_output()' {
run echo 'have'
assert_output
}
On failure, an error message is displayed.
-- no output --
expected non-empty output, but output was empty
--
Partial matching can be enabled with the --partial
option (-p
for short).
When used, the assertion fails if the expected substring is not found in $output
.
@test 'assert_output() partial matching' {
run echo 'ERROR: no such file or directory'
assert_output --partial 'SUCCESS'
}
On failure, the substring and the output are displayed.
-- output does not contain substring --
substring : SUCCESS
output : ERROR: no such file or directory
--
This option and regular expression matching (--regexp
or -e
) are mutually exclusive.
An error is displayed when used simultaneously.
Regular expression matching can be enabled with the --regexp
option (-e
for short).
When used, the assertion fails if the extended regular expression does not match $output
.
Note: The anchors
^
and$
bind to the beginning and the end of the entire output (not individual lines), respectively.
@test 'assert_output() regular expression matching' {
run echo 'Foobar 0.1.0'
assert_output --regexp '^Foobar v[0-9]+\.[0-9]+\.[0-9]$'
}
On failure, the regular expression and the output are displayed.
-- regular expression does not match output --
regexp : ^Foobar v[0-9]+\.[0-9]+\.[0-9]$
output : Foobar 0.1.0
--
An error is displayed if the specified extended regular expression is invalid.
This option and partial matching (--partial
or -p
) are mutually exclusive.
An error is displayed when used simultaneously.
The expected output can be specified via standard input (also heredoc/herestring) with the -
/--stdin
option.
@test 'assert_output() with pipe' {
run echo 'hello'
echo 'hello' | assert_output -
}
@test 'assert_output() with herestring' {
run echo 'hello'
assert_output - <<< hello
}
refute_output
This function helps to verify that a command or function produces the correct output by checking that the specified unexpected output does not match the actual output.
Matching can be literal (default), partial or regular expression.
This function is the logical complement of assert_output
.
By default, literal matching is performed.
The assertion fails if $output
equals the unexpected output.
@test 'refute_output()' {
run echo 'want'
refute_output 'want'
}
On failure, the output is displayed.
-- output equals, but it was expected to differ --
output : want
--
If output is longer than one line it is displayed in multi-line format.
To assert that there is no output at all, simply omit the matching argument.
@test 'refute_output()' {
run foo --silent
refute_output
}
On failure, an error message is displayed.
-- unexpected output --
expected no output, but output was non-empty
--
Partial matching can be enabled with the --partial
option (-p
for short).
When used, the assertion fails if the unexpected substring is found in $output
.
@test 'refute_output() partial matching' {
run echo 'ERROR: no such file or directory'
refute_output --partial 'ERROR'
}
On failure, the substring and the output are displayed.
-- output should not contain substring --
substring : ERROR
output : ERROR: no such file or directory
--
This option and regular expression matching (--regexp
or -e
) are mutually exclusive.
An error is displayed when used simultaneously.
Regular expression matching can be enabled with the --regexp
option (-e
for short).
When used, the assertion fails if the extended regular expression matches $output
.
Note: The anchors
^
and$
bind to the beginning and the end of the entire output (not individual lines), respectively.
@test 'refute_output() regular expression matching' {
run echo 'Foobar v0.1.0'
refute_output --regexp '^Foobar v[0-9]+\.[0-9]+\.[0-9]$'
}
On failure, the regular expression and the output are displayed.
-- regular expression should not match output --
regexp : ^Foobar v[0-9]+\.[0-9]+\.[0-9]$
output : Foobar v0.1.0
--
An error is displayed if the specified extended regular expression is invalid.
This option and partial matching (--partial
or -p
) are mutually exclusive.
An error is displayed when used simultaneously.
The unexpected output can be specified via standard input (also heredoc/herestring) with the -
/--stdin
option.
@test 'refute_output() with pipe' {
run echo 'hello'
echo 'world' | refute_output -
}
@test 'refute_output() with herestring' {
run echo 'hello'
refute_output - <<< world
}
assert_line
Similarly to assert_output
, this function helps to verify that a command or function produces the correct output.
It checks that the expected line appears in the output (default) or in a specific line of it.
Matching can be literal (default), partial or regular expression.
This function is the logical complement of refute_line
.
Warning: Due to a bug in Bats, empty lines are discarded from
${lines[@]}
, causing line indices to change and preventing testing for empty lines.
By default, the entire output is searched for the expected line.
The assertion fails if the expected line is not found in ${lines[@]}
.
@test 'assert_line() looking for line' {
run echo $'have-0\nhave-1\nhave-2'
assert_line 'want'
}
On failure, the expected line and the output are displayed.
Warning: The output displayed does not contain empty lines. See the Warning above for more.
-- output does not contain line --
line : want
output (3 lines):
have-0
have-1
have-2
--
If output is not longer than one line, it is displayed in two-column format.
When the --index <idx>
option is used (-n <idx>
for short), the expected line is matched only against the line identified by the given index.
The assertion fails if the expected line does not equal ${lines[<idx>]}
.
@test 'assert_line() specific line' {
run echo $'have-0\nhave-1\nhave-2'
assert_line --index 1 'want-1'
}
On failure, the index and the compared lines are displayed.
-- line differs --
index : 1
expected : want-1
actual : have-1
--
Partial matching can be enabled with the --partial
option (-p
for short).
When used, a match fails if the expected substring is not found in the matched line.
@test 'assert_line() partial matching' {
run echo $'have 1\nhave 2\nhave 3'
assert_line --partial 'want'
}
On failure, the same details are displayed as for literal matching, except that the substring replaces the expected line.
-- no output line contains substring --
substring : want
output (3 lines):
have 1
have 2
have 3
--
This option and regular expression matching (--regexp
or -e
) are mutually exclusive.
An error is displayed when used simultaneously.
Regular expression matching can be enabled with the --regexp
option (-e
for short).
When used, a match fails if the extended regular expression does not match the line being tested.
Note: As expected, the anchors
^
and$
bind to the beginning and the end of the matched line, respectively.
@test 'assert_line() regular expression matching' {
run echo $'have-0\nhave-1\nhave-2'
assert_line --index 1 --regexp '^want-[0-9]$'
}
On failure, the same details are displayed as for literal matching, except that the regular expression replaces the expected line.
-- regular expression does not match line --
index : 1
regexp : ^want-[0-9]$
line : have-1
--
An error is displayed if the specified extended regular expression is invalid.
This option and partial matching (--partial
or -p
) are mutually exclusive.
An error is displayed when used simultaneously.
refute_line
Similarly to refute_output
, this function helps to verify that a command or function produces the correct output.
It checks that the unexpected line does not appear in the output (default) or in a specific line of it.
Matching can be literal (default), partial or regular expression.
This function is the logical complement of assert_line
.
Warning: Due to a bug in Bats, empty lines are discarded from
${lines[@]}
, causing line indices to change and preventing testing for empty lines.
By default, the entire output is searched for the unexpected line.
The assertion fails if the unexpected line is found in ${lines[@]}
.
@test 'refute_line() looking for line' {
run echo $'have-0\nwant\nhave-2'
refute_line 'want'
}
On failure, the unexpected line, the index of its first match and the output with the matching line highlighted are displayed.
Warning: The output displayed does not contain empty lines. See the Warning above for more.
-- line should not be in output --
line : want
index : 1
output (3 lines):
have-0
> want
have-2
--
If output is not longer than one line, it is displayed in two-column format.
When the --index <idx>
option is used (-n <idx>
for short), the unexpected line is matched only against the line identified by the given index.
The assertion fails if the unexpected line equals ${lines[<idx>]}
.
@test 'refute_line() specific line' {
run echo $'have-0\nwant-1\nhave-2'
refute_line --index 1 'want-1'
}
On failure, the index and the unexpected line are displayed.
-- line should differ --
index : 1
line : want-1
--
Partial matching can be enabled with the --partial
option (-p
for short).
When used, a match fails if the unexpected substring is found in the matched line.
@test 'refute_line() partial matching' {
run echo $'have 1\nwant 2\nhave 3'
refute_line --partial 'want'
}
On failure, in addition to the details of literal matching, the substring is also displayed.
When used with --index <idx>
the substring replaces the unexpected line.
-- no line should contain substring --
substring : want
index : 1
output (3 lines):
have 1
> want 2
have 3
--
This option and regular expression matching (--regexp
or -e
) are mutually exclusive.
An error is displayed when used simultaneously.
Regular expression matching can be enabled with the --regexp
option (-e
for short).
When used, a match fails if the extended regular expression matches the line being tested.
Note: As expected, the anchors
^
and$
bind to the beginning and the end of the matched line, respectively.
@test 'refute_line() regular expression matching' {
run echo $'Foobar v0.1.0\nRelease date: 2015-11-29'
refute_line --index 0 --regexp '^Foobar v[0-9]+\.[0-9]+\.[0-9]$'
}
On failure, in addition to the details of literal matching, the regular expression is also displayed.
When used with --index <idx>
the regular expression replaces the unexpected line.
-- regular expression should not match line --
index : 0
regexp : ^Foobar v[0-9]+\.[0-9]+\.[0-9]$
line : Foobar v0.1.0
--
An error is displayed if the specified extended regular expression is invalid.
This option and partial matching (--partial
or -p
) are mutually exclusive.
An error is displayed when used simultaneously.
assert_regex
This function is similar to assert_equal
but uses pattern matching instead of
equality, by wrapping [[ value =~ pattern ]]
.
Fail if the value (first parameter) does not match the pattern (second parameter).
@test 'assert_regex()' {
assert_regex 'what' 'x$'
}
On failure, the value and the pattern are displayed.
-- values does not match regular expression --
value : what
pattern : x$
--
If the value is longer than one line then it is displayed in multi-line format.
An error is displayed if the specified extended regular expression is invalid.
For description of the matching behavior, refer to the documentation of the
=~
operator in the Bash manual.
_Note: the
BASH_REMATCH
array is available immediately after the assertion succeeds but is fragile; i.e. prone to being overwritten as a side effect of other actions._
refute_regex
This function is similar to refute_equal
but uses pattern matching instead of
equality, by wrapping ! [[ value =~ pattern ]]
.
Fail if the value (first parameter) matches the pattern (second parameter).
@test 'refute_regex()' {
refute_regex 'WhatsApp' 'Threema'
}
On failure, the value, the pattern and the match are displayed.
@test 'refute_regex()' {
refute_regex 'WhatsApp' 'What.'
}
-- value matches regular expression --
value : WhatsApp
pattern : What.
match : Whats
case : sensitive
--
If the value or pattern is longer than one line then it is displayed in multi-line format.
An error is displayed if the specified extended regular expression is invalid.
For description of the matching behavior, refer to the documentation of the
=~
operator in the Bash manual.
_Note: the
BASH_REMATCH
array is available immediately after the assertion fails but is fragile; i.e. prone to being overwritten as a side effect of other actions like callingrun
. Thus, it's good practice to avoid usingBASH_REMATCH
in conjunction withrefute_regex()
. The valuable information the array contains is the matching part of the value which is printed in the failing test log, as mentioned above._