Assertions in design by contract: Difference between revisions
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}
(...)</syntaxhighlight>
=={{header|jq}}==
{{libheader|Jq/assert.jq}}
{{works with|jq}}
jq does not currently support assertions natively though they (and
design by contract) can be simulated as here, using a jq module.
The [https://gist.github.com/pkoppstein/9b0f49a213a5b8083bab094ede06652d "assert.jq"] module
allows assertion checking to be turned on or off; in addition,
execution can be continued or terminated after an assertion violation is detected.
In the following, it is assumed the "debug" mode of assertion checking has been used, e.g.
via the invocation: jq --arg assert debug
This mode allows execution to continue after an assertion violation has been detected.
<syntaxhighlight lang="jq">
include "rc-assert" {search: "."}; # or use the -L command-line option
def averageOfAbsolutes:
. as $values
# pre-condition
| assert(type == "array" and length > 0 and all(type=="number");
"input to averageOfAbsolutes should be a non-empty array of numbers.")
| (map(length) | add/length) as $result
# post-condition
| assert($result >= 0;
$__loc__ + { msg: "Average of absolute values should be non-negative."} )
| $result;
[1, 3], ["hello"]
| averageOfAbsolutes
</syntaxhighlight>
{{output}}
Invocation: jq -n --arg assert debug -f assertions.jq
<pre>
2
["DEBUG:","assertion violation @ input to averageOfAbsolutes should be a non-empty array of numbers. => false"]
5
</pre>
=={{header|Julia}}==
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{{libheader|Wren-assert}}
Wren doesn't support assertions natively though they (and design by contract) can be simulated using a library.
<syntaxhighlight lang="
import "./math" for Nums
// Assert.disabled = true
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