diff options
Diffstat (limited to 'lib/asserts.nix')
-rw-r--r-- | lib/asserts.nix | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/lib/asserts.nix b/lib/asserts.nix index 9ae357cbc935..98e0b490acf2 100644 --- a/lib/asserts.nix +++ b/lib/asserts.nix @@ -16,11 +16,15 @@ rec { assertMsg :: Bool -> String -> Bool */ # TODO(Profpatsch): add tests that check stderr - assertMsg = pred: msg: + assertMsg = + # Predicate that needs to succeed, otherwise `msg` is thrown + pred: + # Message to throw in case `pred` fails + msg: pred || builtins.throw msg; - /* Specialized `assertMsg` for checking if val is one of the elements - of a list. Useful for checking enums. + /* Specialized `assertMsg` for checking if `val` is one of the elements + of the list `xs`. Useful for checking enums. Example: let sslLibrary = "libressl"; @@ -33,7 +37,14 @@ rec { Type: assertOneOf :: String -> ComparableVal -> List ComparableVal -> Bool */ - assertOneOf = name: val: xs: assertMsg + assertOneOf = + # The name of the variable the user entered `val` into, for inclusion in the error message + name: + # The value of what the user provided, to be compared against the values in `xs` + val: + # The list of valid values + xs: + assertMsg (lib.elem val xs) "${name} must be one of ${ lib.generators.toPretty {} xs}, but is: ${ |