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45 lines
1.2 KiB
Nix
45 lines
1.2 KiB
Nix
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{ lib }:
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rec {
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/* Print a trace message if pred is false.
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Intended to be used to augment asserts with helpful error messages.
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Example:
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assertMsg false "nope"
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=> false
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stderr> trace: nope
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assert (assertMsg ("foo" == "bar") "foo is not bar, silly"); ""
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stderr> trace: foo is not bar, silly
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stderr> assert failed at …
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Type:
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assertMsg :: Bool -> String -> Bool
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*/
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# TODO(Profpatsch): add tests that check stderr
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assertMsg = pred: msg:
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if pred
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then true
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else builtins.trace msg false;
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/* Specialized `assertMsg` for checking if val is one of the elements
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of a list. Useful for checking enums.
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Example:
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let sslLibrary = "libressl"
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in assertOneOf "sslLibrary" sslLibrary [ "openssl" "bearssl" ]
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=> false
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stderr> trace: sslLibrary must be one of "openssl", "bearssl", but is: "libressl"
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Type:
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assertOneOf :: String -> ComparableVal -> List ComparableVal -> Bool
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*/
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assertOneOf = name: val: xs: assertMsg
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(lib.elem val xs)
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"${name} must be one of ${
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lib.generators.toPretty {} xs}, but is: ${
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lib.generators.toPretty {} val}";
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}
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