lib/debug: document module & functions, prune imports

This commit is contained in:
Profpatsch 2018-04-03 08:48:04 +02:00
parent e49f40e1ca
commit 5012c49fc0

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@ -1,28 +1,67 @@
/* Collection of functions useful for debugging
broken nix expressions.
* `trace`-like functions take two values, print
the first to stderr and return the second.
* `traceVal`-like functions take one argument
which both printed and returned.
* `traceSeq`-like functions fully evaluate their
traced value before printing (not just to weak
head normal form like trace does by default).
* Functions that end in `-Fn` take an additional
function as their first argument, which is applied
to the traced value before it is printed.
*/
{ lib }:
let
inherit (builtins) trace attrNamesToStr isAttrs isList isInt
isString isBool head substring attrNames;
inherit (lib) all id mapAttrsFlatten elem isFunction;
inherit (builtins) trace isAttrs isList isInt
head substring attrNames;
inherit (lib) id elem isFunction;
in
rec {
traceIf = p: msg: x: if p then trace msg x else x;
# -- TRACING --
/* Trace msg, but only if pred is true.
Example:
traceIf true "hello" 3
trace: hello
=> 3
*/
traceIf = pred: msg: x: if pred then trace msg x else x;
/* Trace the value and also return it.
Example:
traceValFn (v: "mystring ${v}") "foo"
trace: mystring foo
=> "foo"
*/
traceValFn = f: x: trace (f x) x;
traceVal = traceValFn id;
# strict trace functions (traced structure is fully evaluated and printed)
/* `builtins.trace`, but the value is `builtins.deepSeq`ed first. */
/* `builtins.trace`, but the value is `builtins.deepSeq`ed first.
Example:
trace { a.b.c = 3; } null
trace: { a = <CODE>; }
=> null
traceSeq { a.b.c = 3; } null
trace: { a = { b = { c = 3; }; }; }
=> null
*/
traceSeq = x: y: trace (builtins.deepSeq x x) y;
/* Like `traceSeq`, but only down to depth n.
* This is very useful because lots of `traceSeq` usages
* lead to an infinite recursion.
/* Like `traceSeq`, but only evaluate down to depth n.
This is very useful because lots of `traceSeq` usages
lead to an infinite recursion.
Example:
traceSeqN 2 { a.b.c = 3; } null
trace: { a = { b = {}; }; }
=> null
*/
traceSeqN = depth: x: y: with lib;
let snip = v: if isList v then noQuotes "[]" v
@ -37,15 +76,42 @@ rec {
in trace (generators.toPretty { allowPrettyValues = true; }
(modify depth snip x)) y;
/* `traceSeq`, but the same value is traced and returned */
/* A combination of `traceVal` and `traceSeq` */
traceValSeqFn = f: v: traceVal f (builtins.deepSeq v v);
traceValSeq = traceValSeqFn id;
/* `traceValSeq` but with fixed depth */
/* A combination of `traceVal` and `traceSeqN`. */
traceValSeqNFn = f: depth: v: traceSeqN depth (f v) v;
traceValSeqN = traceValSeqNFn id;
# this can help debug your code as well - designed to not produce thousands of lines
# -- TESTING --
/* Evaluate a set of tests. A test is an attribute set {expr,
expected}, denoting an expression and its expected result. The
result is a list of failed tests, each represented as {name,
expected, actual}, denoting the attribute name of the failing
test and its expected and actual results. Used for regression
testing of the functions in lib; see tests.nix for an example.
Only tests having names starting with "test" are run.
Add attr { tests = ["testName"]; } to run these test only
*/
runTests = tests: lib.concatLists (lib.attrValues (lib.mapAttrs (name: test:
let testsToRun = if tests ? tests then tests.tests else [];
in if (substring 0 4 name == "test" || elem name testsToRun)
&& ((testsToRun == []) || elem name tests.tests)
&& (test.expr != test.expected)
then [ { inherit name; expected = test.expected; result = test.expr; } ]
else [] ) tests));
# create a test assuming that list elements are true
# usage: { testX = allTrue [ true ]; }
testAllTrue = expr: { inherit expr; expected = map (x: true) expr; };
# -- DEPRECATED --
traceShowVal = x: trace (showVal x) x;
traceShowValMarked = str: x: trace (str + showVal x) x;
@ -100,28 +166,6 @@ rec {
+ "and will be removed in the next release." )
(lib.mapAttrs (a: v: lib.addErrorContext "while evaluating ${a}" v) attrs);
/* Evaluate a set of tests. A test is an attribute set {expr,
expected}, denoting an expression and its expected result. The
result is a list of failed tests, each represented as {name,
expected, actual}, denoting the attribute name of the failing
test and its expected and actual results. Used for regression
testing of the functions in lib; see tests.nix for an example.
Only tests having names starting with "test" are run.
Add attr { tests = ["testName"]; } to run these test only
*/
runTests = tests: lib.concatLists (lib.attrValues (lib.mapAttrs (name: test:
let testsToRun = if tests ? tests then tests.tests else [];
in if (substring 0 4 name == "test" || elem name testsToRun)
&& ((testsToRun == []) || elem name tests.tests)
&& (test.expr != test.expected)
then [ { inherit name; expected = test.expected; result = test.expr; } ]
else [] ) tests));
# create a test assuming that list elements are true
# usage: { testX = allTrue [ true ]; }
testAllTrue = expr: { inherit expr; expected = map (x: true) expr; };
# example: (traceCallXml "myfun" id 3) will output something like
# calling myfun arg 1: 3 result: 3
# this forces deep evaluation of all arguments and the result!