diff options
author | Profpatsch <mail@profpatsch.de> | 2018-08-08 19:26:52 +0200 |
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committer | Profpatsch <mail@profpatsch.de> | 2018-09-06 18:14:27 +0200 |
commit | efdf618330a22f837f0e5e446028e918a5b4dd8a (patch) | |
tree | 6b9ad4353a2e470a3bccbbdca89247047263062b /lib/asserts.nix | |
parent | 3e45b61a9920466a8ea06b8ad9350d56ade435bc (diff) |
lib: move assertMsg and assertOneOf to their own library file
Since the `assertOneOf` uses `lib.generators`, they are not really trivial
anymore and should go into their own library file.
Diffstat (limited to 'lib/asserts.nix')
-rw-r--r-- | lib/asserts.nix | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/lib/asserts.nix b/lib/asserts.nix new file mode 100644 index 000000000000..8a5f1fb3feb7 --- /dev/null +++ b/lib/asserts.nix @@ -0,0 +1,44 @@ +{ lib }: + +rec { + + /* Print a trace message if pred is false. + Intended to be used to augment asserts with helpful error messages. + + Example: + assertMsg false "nope" + => false + stderr> trace: nope + + assert (assertMsg ("foo" == "bar") "foo is not bar, silly"); "" + stderr> trace: foo is not bar, silly + stderr> assert failed at … + + 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}"; + +} |