tvl-depot/nix/runTestsuite/default.nix
Profpatsch c8e888c1d2 feat(nix/runTestsuite): add runTestsuite
This is a very simple test suite for nix expressions.
It should help us set up a good suite of unit tests for our nix-based
stuff.

Since we allow import from derivation, these tests can also depend on
derivations and e.g. use `builtins.readFile` to check outputs.

This is a first PoC to get us going, we can always replace it by
something different in the future if we don’t like it.

Change-Id: I206c7b624db2b1dabd9c73ffce4f87e658919958
Reviewed-on: https://cl.tvl.fyi/c/depot/+/662
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: tazjin <mail@tazj.in>
2020-06-28 03:52:40 +00:00

121 lines
3 KiB
Nix
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

{ lib, pkgs, depot, ... }:
# Run a nix testsuite.
#
# The tests are simple assertions on the nix level,
# and can use derivation outputs if IfD is enabled.
#
# You build a testsuite by bundling assertions into
# “it”s and then bundling the “it”s into a testsuite.
#
# Running the testsuite will abort evaluation if
# any assertion fails.
#
# Example:
#
# runTestsuite "myFancyTestsuite" [
# (it "does an assertion" [
# (assertEq "42 is equal to 42" "42" "42")
# (assertEq "also 23" 23 23)
# ])
# (it "frmbls the brlbr" [
# (assertEq true false)
# ])
# ]
#
# will fail the second it group because true is not false.
let
inherit (depot.nix.yants) sum struct string any unit defun list;
# rewrite the builtins.partition result
# to use `ok` and `err` instead of `right` and `wrong`.
partitionTests = pred: xs:
let res = builtins.partition pred xs;
in {
ok = res.right;
err = res.wrong;
};
# The result of an assert,
# either its true (yep) or false (nope).
# If its nope, we return the left and right
# side of the assert, together with the description.
AssertResult =
sum "AssertResult" {
yep = struct "yep" {
test = string;
};
nope = struct "nope" {
test = string;
left = any;
right = any;
};
};
# Result of an it. An it is a bunch of asserts
# bundled up with a good description of what is tested.
ItResult =
struct "ItResult" {
it-desc = string;
asserts = list AssertResult;
};
# assert that left and right values are equal
assertEq = defun [ string any any AssertResult ]
(desc: left: right:
if left == right
then { yep = { test = desc; }; }
else { nope = {
test = desc;
inherit left right;
};
});
# Annotate a bunch of asserts with a descriptive name
it = desc: asserts: {
it-desc = desc;
inherit asserts;
};
# Run a bunch of its and check whether all asserts are yep.
# If not, abort evaluation with `throw`
# and print the result of the test suite.
#
# Takes a test suite name as first argument.
runTestsuite = defun [ string (list ItResult) unit ]
(name: itResults:
let
goodAss = ass: {
good = AssertResult.match ass {
yep = _: true;
nope = _: false;
};
x = ass;
};
goodIt = it: {
inherit (it) it-desc;
asserts = partitionTests (ass:
AssertResult.match ass {
yep = _: true;
nope = _: false;
}) it.asserts;
};
goodIts = partitionTests (it: (goodIt it).asserts.err == []);
res = goodIts itResults;
in
if res.err == []
then {}
# TODO(Profpatsch): pretty printing of results
# and probably also somewhat easier to read output
else throw
( "testsuite ${name} failed!\n"
+ lib.generators.toPretty {} res));
in {
inherit
assertEq
it
runTestsuite
;
}