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Diffstat (limited to 'lib/trivial.nix')
-rw-r--r-- | lib/trivial.nix | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/lib/trivial.nix b/lib/trivial.nix index bba284548d9..f1001ee10ca 100644 --- a/lib/trivial.nix +++ b/lib/trivial.nix @@ -203,11 +203,29 @@ rec { Type: assertMsg :: Bool -> String -> Bool */ + # TODO(Profpatsch): add tests that check stderr assertMsg = pred: msg: if pred then true else builtins.trace msg false; + /* Specialized `assertMsg` for checking if val is one of the elements + of a list. Useful for checking enums. + + Example: + let sslLibrary = "libressl" + in assertOneOf "sslLibrary" sslLibrary [ "openssl" "bearssl" ] + => false + stderr> trace: sslLibrary must be one of "openssl", "bearssl", but is: "libressl" + + Type: + assertOneOf :: String -> ComparableVal -> List ComparableVal -> Bool + */ + assertOneOf = name: val: xs: assertMsg + (lib.elem val xs) + "${name} must be one of ${ + lib.generators.toPretty {} xs}, but is: ${ + lib.generators.toPretty {} val}"; ## Function annotations |