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Testament is an advanced automatic unittests runner for Nim tests, is used for the development of Nim itself, offers process isolation for your tests, it can generate statistics about test cases, supports multiple targets (C, C++, ObjectiveC, JavaScript, etc.), simulated Dry-Runs, has logging, can generate HTML reports, skip tests from a file, and more, so can be useful to run your tests, even the most complex ones.

Test files location

By default, Testament looks for test files on "./tests/category/*.nim". You can overwrite this pattern glob using pattern <glob>. The default working directory path can be changed using --directory:"folder/subfolder/".

Testament uses the nim compiler on PATH. You can change that using --nim:"folder/subfolder/nim". Running JavaScript tests with --targets:"js" requires a working NodeJS on PATH.


p|pat|pattern <glob> run all the tests matching the given pattern all run all tests inside of category folders c|cat|category <category> run all the tests of a certain category r|run <test> run single test file html generate testresults.html from the database


print results to the console
print commands (compiling and running tests)
see what tests would be run but don't run them (for debugging)
only show failing/ignored tests
--targets:"c cpp js objc" run tests for specified targets (default: c)
use a particular nim executable (default: $PATH/nim)
Change to directory dir before reading the tests or doing anything else.
Turn messages coloring on|off.
Disable or enable backend logging. By default turned on.
Enable or disable megatest. Default is on.
Enable or disable valgrind support. Default is on.
Read tests to skip from file - one test per line, # comments ignored

Running a single test

This is a minimal example to understand the basics, not very useful for production, but easy to understand:

$ mkdir -p tests/category
$ echo "assert 42 == 42" > tests/category/test0.nim
$ testament run tests/category/test0.nim
PASS: tests/category/test0.nim c                           ( 0.2 sec)
$ testament r tests/category/test0
PASS: tests/category/test0.nim C                           ( 0.2 sec)

Running all tests from a directory

This will run all tests in the top level tests/ directory. NOTE: these tests are skipped by testament all.

$ testament pattern "tests/*.nim"

To search for tests deeper in a directory, use

$ testament pattern "tests/**/*.nim"    # one level deeper
$ testament pattern "tests/**/**/*.nim" # two levels deeper

HTML Reports

Generate HTML Reports testresults.html from unittests, you have to run at least 1 test before generating a report:

$ testament html

Writing Unit tests

Example "template" to edit and write a Testament unittest:

discard """
  # What actions to expect completion on.
  # Options:
  #   "compile": expect successful compilation
  #   "run": expect successful compilation and execution
  #   "reject": expect failed compilation. The "reject" action can catch
  #             {.error.} pragmas but not {.fatal.} pragmas because
  #             {.fatal.} pragmas guarantee that compilation will be aborted.
  action: "run"
  # The exit code that the test is expected to return. Typically, the default
  # value of 0 is fine. Note that if the test will be run by valgrind, then
  # the test will exit with either a code of 0 on success or 1 on failure.
  exitcode: 0
  # Provide an `output` string to assert that the test prints to standard out
  # exactly the expected string. Provide an `outputsub` string to assert that
  # the string given here is a substring of the standard out output of the
  # test (the output includes both the compiler and test execution output).
  output: ""
  outputsub: ""
  # Whether to sort the output lines before comparing them to the desired
  # output.
  sortoutput: true
  # Each line in the string given here appears in the same order in the
  # compiler output, but there may be more lines that appear before, after, or
  # in between them.
  nimout: '''
a very long,
  # This is the Standard Input the test should take, if any.
  input: ""
  # Error message the test should print, if any.
  errormsg: ""
  # Can be run in batch mode, or not.
  batchable: true
  # Can be run Joined with other tests to run all together, or not.
  joinable: true
  # On Linux 64-bit machines, whether to use Valgrind to check for bad memory
  # accesses or memory leaks. On other architectures, the test will be run
  # as-is, without Valgrind.
  # Options:
  #   true: run the test with Valgrind
  #   false: run the without Valgrind
  #   "leaks": run the test with Valgrind, but do not check for memory leaks
  valgrind: false   # Can use Valgrind to check for memory leaks, or not (Linux 64Bit only).
  # Command the test should use to run. If left out or an empty string is
  # provided, the command is taken to be:
  # "nim $target --hints:on -d:testing --nimblePath:build/deps/pkgs $options $file"
  # Subject to variable interpolation.
  cmd: "nim c -r $file"
  # Maximum generated temporary intermediate code file size for the test.
  maxcodesize: 666
  # Timeout seconds to run the test. Fractional values are supported.
  timeout: 1.5
  # Targets to run the test into (c, cpp, objc, js). Defaults to c.
  targets: "c js"
  # flags with which to run the test, delimited by `;`
  matrix: "; -d:release; -d:caseFoo -d:release"
  # Conditions that will skip this test. Use of multiple "disabled" clauses
  # is permitted.
  disabled: "bsd"   # Can disable OSes...
  disabled: "win"
  disabled: "32bit" # ...or architectures
  disabled: "i386"
  disabled: "azure" # ...or pipeline runners
  disabled: true    # ...or can disable the test entirely

assert true
assert 42 == 42, "Assert error message"

Inline hints, warnings and errors (notes)

Testing the line, column, kind and message of hints, warnings and errors can be written inline like so:

{.warning: "warning!!"} #[tt.Warning
         ^ warning!! [User] ]#

The opening #[tt. marks the message line. The ^ marks the message column.

Inline messages can be combined with nimout when nimoutFull is false (default). This allows testing for expected messages from other modules:

discard """
  nimout: "config.nims(1, 1) Hint: some hint message [User]"
{.warning: "warning!!"} #[tt.Warning
         ^ warning!! [User] ]#

Multiple messages for a line can be checked by delimiting messages with ';':

discard """
  matrix: "--errorMax:0 --styleCheck:error"

proc generic_proc*[T](a_a: int) = #[tt.Error
     ^ 'generic_proc' should be: 'genericProc'; tt.Error
                      ^ 'a_a' should be: 'aA' ]#

Use --errorMax:0 in matrix, or cmd: "nim check $file" when testing for multiple 'Error' messages.

Output message variable interpolation

errormsg, nimout, and inline messages are subject to these variable interpolations:

  • ${/} - platform's directory separator
  • $file - the filename (without directory) of the test

All other $ characters need escaped as $$.

Cmd variable interpolation

The cmd option is subject to these variable interpolations:

  • $target - the compilation target, e.g. c.
  • $options - the options for the compiler.
  • $file - the file path of the test.
  • $filedir - the directory of the test file.
discard """
  cmd: "nim $target --nimblePath:./nimbleDir/simplePkgs $options $file"

All other $ characters need escaped as $$.

Unit test Examples

Expected to fail:

discard """
  errormsg: "undeclared identifier: 'not_defined'"
assert not_defined == "not_defined", "not_defined is not defined"

Non-Zero exit code:

discard """
  exitcode: 1
quit "Non-Zero exit code", 1

Standard output checking:

discard """
  output: '''

for i in 0..5: echo i

JavaScript tests:

discard """
  targets: "js"
when defined(js):
  import std/jsconsole
  console.log("My Frontend Project")

Compile-time tests:

discard """
  action: "compile"
static: assert 9 == 9, "Compile time assert"

Tests without Spec:

assert 1 == 1

See also: