contributing.rst

Writing tests

Not all the tests follow this scheme, feel free to change the ones that don't. Always leave the code cleaner than you found it.

Stdlib

If you change the stdlib (anything under lib/), put a test in the file you changed. Add the tests under an when isMainModule: condition so they only get executed when the tester is building the file. Each test should be in a separate block: statement, such that each has its own scope. Use boolean conditions and doAssert for the testing by itself, don't rely on echo statements or similar.

Sample test:

when isMainModule:
  block: # newSeqWith tests
    var seq2D = newSeqWith(4, newSeq[bool](2))
    seq2D[0][0] = true
    seq2D[1][0] = true
    seq2D[0][1] = true
    doAssert seq2D == @[@[true, true], @[true, false],
                        @[false, false], @[false, false]]

Compiler

The tests for the compiler work differently, they are all located in tests/. Each test has its own file, which is different from the stdlib tests. All test files are prefixed with t. If you want to create a file for import into another test only, use the prefix m.

At the beginning of every test is the expected side of the test. Possible keys are:

• output: The expected output, most likely via echo
• exitcode: Exit code of the test (via exit(number))
• errormsg: The expected error message
• file: The file the errormsg
• line: The line the errormsg was produced at

An example for a test:

discard """
  errormsg: "type mismatch: got (PTest)"
"""

type
  PTest = ref object

proc test(x: PTest, y: int) = nil

var buf: PTest
buf.test()

Running tests

You can run the tests with

./koch tests

which will run a good subset of tests. Some tests may fail. If you only want to see the output of failing tests, go for

./koch tests --failing all

You can also run only a single category of tests. A category is a subdirectory in the tests directory. There are a couple of special categories; for a list of these, see tests/testament/categories.nim, at the bottom.

./koch tests c lib

Comparing tests

Because some tests fail in the current devel branch, not every fail after your change is necessarily caused by your changes.

The tester can compare two test runs. First, you need to create the reference test. You'll also need to the commit id, because that's what the tester needs to know in order to compare the two.

git checkout devel
DEVEL_COMMIT=$(git rev-parse HEAD)
./koch tests

Then switch over to your changes and run the tester again.

git checkout your-changes
./koch tests

Then you can ask the tester to create a testresults.html which will tell you if any new tests passed/failed.

./koch tests --print html $DEVEL_COMMIT

Deprecation

Backward compatibility is important, so if you are renaming a proc or a type, you can use

{.deprecated: [oldName: new_name].}

Or you can simply use

proc oldProc() {.deprecated.}

to mark a symbol as deprecated. Works for procs/types/vars/consts, etc. Note that currently the deprecated statement does not work well with overloading so for routines the latter variant is better.

Deprecated pragma in the manual.

Documentation

When contributing new procedures, be sure to add documentation, especially if the procedure is exported from the module. Documentation begins on the line following the proc definition, and is prefixed by ## on each line.

Code examples are also encouraged. The RestructuredText Nim uses has a special syntax for including examples.

proc someproc*(): string =
  ## Return "something"
  ##
  ## .. code-block:: nim
  ##
  ##  echo someproc() # "something"
  result = "something" # single-hash comments do not produce documentation

The .. code-block:: nim followed by a newline and an indentation instructs the nim doc and nim doc2 commands to produce syntax-highlighted example code with the documentation.

When forward declaration is used, the documentation should be included with the first appearance of the proc.

proc hello*(): string
  ## Put documentation here
proc nothing() = discard
proc hello*(): string =
  ## Ignore this
  echo "hello"

The preferred documentation style is to begin with a capital letter and use the imperative (command) form. That is, between:

proc hello*(): string =
  # Return "hello"
  result = "hello"

or

proc hello*(): string =
  # says hello
  result = "hello"

the first is preferred.

The Git stuff

General commit rules

1. All changes introduced by the commit (diff lines) must be related to the subject of the commit.

   If you change some other unrelated to the subject parts of the file, because your editor reformatted automatically the code or whatever different reason, this should be excluded from the commit.

   Tip: Never commit everything as is using git commit -a, but review carefully your changes with git add -p.

2. Changes should not introduce any trailing whitespace.

   Always check your changes for whitespace errors using git diff --check or add following pre-commit hook:

   #!/bin/sh
   git diff --check --cached || exit $?

3. Describe your commit and use your common sense.