forked from mirrors/nixpkgs
44 lines
1.3 KiB
Nix
44 lines
1.3 KiB
Nix
{ lib, runCommand, emptyFile, nix-diff }:
|
|
|
|
/*
|
|
Checks that two packages produce the exact same build instructions.
|
|
|
|
This can be used to make sure that a certain difference of configuration,
|
|
such as the presence of an overlay does not cause a cache miss.
|
|
|
|
When the derivations are equal, the return value is an empty file.
|
|
Otherwise, the build log explains the difference via `nix-diff`.
|
|
|
|
Example:
|
|
|
|
testEqualDerivation
|
|
"The hello package must stay the same when enabling checks."
|
|
hello
|
|
(hello.overrideAttrs(o: { doCheck = true; }))
|
|
|
|
*/
|
|
assertion: a: b:
|
|
let
|
|
drvA = builtins.unsafeDiscardOutputDependency a.drvPath or (throw "testEqualDerivation second argument must be a package");
|
|
drvB = builtins.unsafeDiscardOutputDependency b.drvPath or (throw "testEqualDerivation third argument must be a package");
|
|
name =
|
|
if a?name
|
|
then lib.strings.sanitizeDerivationName "testEqualDerivation-${a.name}"
|
|
else "testEqualDerivation";
|
|
in
|
|
if drvA == drvB then
|
|
emptyFile
|
|
else
|
|
runCommand name
|
|
{
|
|
inherit assertion drvA drvB;
|
|
nativeBuildInputs = [ nix-diff ];
|
|
} ''
|
|
echo "$assertion"
|
|
echo "However, the derivations differ:"
|
|
echo
|
|
echo nix-diff $drvA $drvB
|
|
nix-diff $drvA $drvB
|
|
exit 1
|
|
''
|