Module unittest

This module implements boilerplate to make unit testing easy.

The test status and name is printed after any output or traceback.

Tests can be nested, however failure of a nested test will not mark the parent test as failed. Setup and teardown are inherited. Setup can be overridden locally.

Compiled test files return the number of failed test as exit code, while nim c -r <testfile.nim> exits with 0 or 1

Running a single test

Specify the test name as a command line argument.

nim c -r test "my test name" "another test"

Multiple arguments can be used.

Running a single test suite

Specify the suite name delimited by "::".

nim c -r test "my test name::"

Selecting tests by pattern

A single "*" can be used for globbing.

Delimit the end of a suite name with "::".

Tests matching any of the arguments are executed.

nim c -r test fast_suite::mytest1 fast_suite::mytest2
nim c -r test "fast_suite::mytest*"
nim c -r test "auth*::" "crypto::hashing*"
# Run suites starting with 'bug #' and standalone tests starting with '#'
nim c -r test 'bug #*::' '::#*'


suite "description for this stuff":
  echo "suite setup: run once before the tests"
    echo "run before each test"
    echo "run after each test"
  test "essential truths":
    # give up and stop if this fails
  test "slightly less obvious stuff":
    # print a nasty message and move on, skipping
    # the remainder of this block
    check(1 != 1)
    check("asd"[2] == 'd')
  test "out of bounds error is thrown on bad access":
    let v = @[1, 2, 3]  # you can do initialization here
      discard v[4]
  echo "suite teardown: run once after the tests"


macros, strutils, streams, times, sets, os, terminal


TestStatus = enum
The status of a test when it is done.
OutputLevel = enum
  PRINT_ALL,                  ## Print as much as possible.
  PRINT_FAILURES,             ## Print only the failed tests.
  PRINT_NONE                  ## Print nothing.
The output verbosity of the tests.
TestResult = object
  suiteName*: string
  testName*: string            ## Name of the test case
  status*: TestStatus
Name of the test suite that contains this test case. Can be nil if the test case is not in a suite.
OutputFormatter = ref object of RootObj
ConsoleOutputFormatter = ref object of OutputFormatter
  colorOutput: bool
  outputLevel: OutputLevel     ## Set the verbosity of test results.
                         ## Default is ``PRINT_ALL``, unless
                         ## the ``NIMTEST_OUTPUT_LVL`` environment
                         ## variable is set for the non-js target.
  isInSuite: bool
  isInTest: bool
Have test results printed in color. Default is true for the non-js target, for which stdout is a tty. Setting the environment variable NIMTEST_COLOR to always or never changes the default for the non-js target to true or false respectively. The deprecated environment variable NIMTEST_NO_COLOR, when set, changes the defualt to true, if NIMTEST_COLOR is undefined.
JUnitOutputFormatter = ref object of OutputFormatter
  stream: Stream
  testErrors: seq[string]
  testStartTime: float
  testStackTrace: string


abortOnError: bool
Set to true in order to quit immediately on fail. Default is false, unless the NIMTEST_ABORT_ON_ERROR environment variable is set for the non-js target.


proc addOutputFormatter(formatter: OutputFormatter) {...}{.raises: [], tags: [].}
proc newConsoleOutputFormatter(outputLevel: OutputLevel = PRINT_ALL;
                              colorOutput = true): ConsoleOutputFormatter {...}{.
    raises: [], tags: [].}
proc defaultConsoleFormatter(): ConsoleOutputFormatter {...}{.raises: [],
    tags: [ReadEnvEffect].}
"is greater" operator. This is the same as y < x.
proc newJUnitOutputFormatter(stream: Stream): JUnitOutputFormatter {...}{.
    raises: [Exception], tags: [WriteIOEffect].}
Creates a formatter that writes report to the specified stream in JUnit format. The stream is NOT closed automatically when the test are finished, because the formatter has no way to know when all tests are finished. You should invoke formatter.close() to finalize the report.
proc close(formatter: JUnitOutputFormatter) {...}{.raises: [Exception],
    tags: [WriteIOEffect].}
Completes the report and closes the underlying stream.
proc checkpoint(msg: string) {...}{.raises: [], tags: [].}
Set a checkpoint identified by msg. Upon test failure all checkpoints encountered so far are printed out. Example:
checkpoint("Checkpoint A")
check((42, "the Answer to life and everything") == (1, "a"))
checkpoint("Checkpoint B")

outputs "Checkpoint A" once it fails.

proc disableParamFiltering() {...}{.raises: [], tags: [].}
disables filtering tests with the command line params


method suiteStarted(formatter: OutputFormatter; suiteName: string) {...}{.base, gcsafe,
    raises: [], tags: [].}
method testStarted(formatter: OutputFormatter; testName: string) {...}{.base, gcsafe,
    raises: [], tags: [].}
method failureOccurred(formatter: OutputFormatter; checkpoints: seq[string];
                      stackTrace: string) {...}{.base, gcsafe, raises: [], tags: [].}
stackTrace is provided only if the failure occurred due to an exception. checkpoints is never nil.
method testEnded(formatter: OutputFormatter; testResult: TestResult) {...}{.base, gcsafe,
    raises: [], tags: [].}
method suiteEnded(formatter: OutputFormatter) {...}{.base, gcsafe, raises: [], tags: [].}
method suiteStarted(formatter: ConsoleOutputFormatter; suiteName: string) {...}{.
    raises: [Exception, IOError], tags: [RootEffect, WriteIOEffect].}
Echoes styles arguments to stdout using styledWriteLine.
method testStarted(formatter: ConsoleOutputFormatter; testName: string) {...}{.raises: [],
    tags: [].}
method failureOccurred(formatter: ConsoleOutputFormatter; checkpoints: seq[string];
                      stackTrace: string) {...}{.raises: [], tags: [].}
"is greater" operator. This is the same as y < x.
method testEnded(formatter: ConsoleOutputFormatter; testResult: TestResult) {...}{.
    raises: [Exception, IOError], tags: [RootEffect, WriteIOEffect].}
unequals operator. This is a shorthand for not (x == y).
method suiteEnded(formatter: ConsoleOutputFormatter) {...}{.raises: [], tags: [].}
method suiteStarted(formatter: JUnitOutputFormatter; suiteName: string) {...}{.
    raises: [Exception, ValueError], tags: [WriteIOEffect].}
method testStarted(formatter: JUnitOutputFormatter; testName: string) {...}{.raises: [],
    tags: [TimeEffect].}
method failureOccurred(formatter: JUnitOutputFormatter; checkpoints: seq[string];
                      stackTrace: string) {...}{.raises: [], tags: [].}
stackTrace is provided only if the failure occurred due to an exception. checkpoints is never nil.
method testEnded(formatter: JUnitOutputFormatter; testResult: TestResult) {...}{.
    raises: [Exception, ValueError], tags: [TimeEffect, WriteIOEffect].}
"is greater" operator. This is the same as y < x.
method suiteEnded(formatter: JUnitOutputFormatter) {...}{.raises: [Exception],
    tags: [WriteIOEffect].}


macro check(conditions: untyped): untyped
Verify if a statement or a list of statements is true. A helpful error message and set checkpoints are printed out on failure (if outputLevel is not PRINT_NONE). Example:
import strutils

check("AKB48".toLowerAscii() == "akb48")

let teams = {'A', 'K', 'B', '4', '8'}

  "AKB48".toLowerAscii() == "akb48"
  'C' in teams
macro expect(exceptions: varargs[typed]; body: untyped): untyped
Test if body raises an exception found in the passed exceptions. The test passes if the raised exception is part of the acceptable exceptions. Otherwise, it fails. Example:
import math, random
proc defectiveRobot() =
  case random(1..4)
  of 1: raise newException(OSError, "CANNOT COMPUTE!")
  of 2: discard parseInt("Hello World!")
  of 3: raise newException(IOError, "I can't do that Dave.")
  else: assert 2 + 2 == 5

expect IOError, OSError, ValueError, AssertionError:


template suite(name, body) {...}{.dirty.}

Declare a test suite identified by name with optional setup and/or teardown section.

A test suite is a series of one or more related tests sharing a common fixture (setup, teardown). The fixture is executed for EACH test.

suite "test suite for addition":
    let result = 4
  test "2 + 2 = 4":
    check(2+2 == result)
  test "(2 + -2) != 4":
    check(2 + -2 != result)
  # No teardown needed

The suite will run the individual test cases in the order in which they were listed. With default global settings the above code prints:

[Suite] test suite for addition
  [OK] 2 + 2 = 4
  [OK] (2 + -2) != 4
template test(name, body) {...}{.dirty.}
Define a single test case identified by name.
test "roses are red":
  let roses = "red"
  check(roses == "red")

The above code outputs:

[OK] roses are red
template fail()
Print out the checkpoints encountered so far and quit if abortOnError is true. Otherwise, erase the checkpoints and indicate the test has failed (change exit code and test status). This template is useful for debugging, but is otherwise mostly used internally. Example:
checkpoint("Checkpoint A")

outputs "Checkpoint A" before quitting.

template skip()
Mark the test as skipped. Should be used directly in case when it is not possible to perform test for reasons depending on outer environment, or certain application logic conditions or configurations. The test code is still executed.
if not isGLConextCreated():
template require(conditions: untyped)
Same as check except any failed test causes the program to quit immediately. Any teardown statements are not executed and the failed test output is not generated.

© 2006–2018 Andreas Rumpf
Licensed under the MIT License.