tvl-depot/nix/tag/tests.nix
sterni 5174c21637 fix(nix/tag): correct no match check in discr
It uses discrDef internally, but passes `null` as the default tag name,
causing Nix to drop the attribute and return an empty attribute set if
the default case is hit. Consequently we need to check for the empty
attribute set, not `null` to figure out if there was no match found.

We can also test this behavior using `assertThrows` which was introduced
after the tag library was originally written.

Change-Id: I45adb2f9602762dfc867956323fb3f5ae4c8bd1d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6904
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI
2022-10-09 13:25:14 +00:00

99 lines
2.1 KiB
Nix

{ depot, lib, verifyTag, discr, discrDef, match, matchLam }:
let
inherit (depot.nix.runTestsuite)
runTestsuite
assertEq
assertThrows
it
;
isTag-test = it "checks whether something is a tag" [
(assertEq "is Tag"
(verifyTag { foo = "bar"; })
{
isTag = true;
name = "foo";
val = "bar";
errmsg = null;
})
(assertEq "is not Tag"
(removeAttrs (verifyTag { foo = "bar"; baz = 42; }) [ "errmsg" ])
{
isTag = false;
name = null;
val = null;
})
];
discr-test = it "can discr things" [
(assertEq "id"
(discr [
{ a = lib.const true; }
] "x")
{ a = "x"; })
(assertEq "bools here, ints there"
(discr [
{ bool = lib.isBool; }
{ int = lib.isInt; }
] 25)
{ int = 25; })
(assertEq "bools here, ints there 2"
(discr [
{ bool = lib.isBool; }
{ int = lib.isInt; }
]
true)
{ bool = true; })
(assertEq "fallback to default"
(discrDef "def" [
{ bool = lib.isBool; }
{ int = lib.isInt; }
] "foo")
{ def = "foo"; })
(assertThrows "throws failing to match"
(discr [
{ fish = x: x == 42; }
] 21))
];
match-test = it "can match things" [
(assertEq "match example"
(
let
success = { res = 42; };
failure = { err = "no answer"; };
matcher = {
res = i: i + 1;
err = _: 0;
};
in
{
one = match success matcher;
two = match failure matcher;
}
)
{
one = 43;
two = 0;
})
(assertEq "matchLam & pipe"
(lib.pipe { foo = 42; } [
(matchLam {
foo = i: if i < 23 then { small = i; } else { big = i; };
bar = _: { small = 5; };
})
(matchLam {
small = i: "yay it was small";
big = i: "whoo it was big!";
})
])
"whoo it was big!")
];
in
runTestsuite "tag" [
isTag-test
discr-test
match-test
]