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.\"
.IX Title "Test::Snapshot 3pm"
.TH Test::Snapshot 3pm "2023-07-12" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
Test::Snapshot \- test against data stored in automatically\-named file
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\&  use Test::Snapshot;
\&  my $got = function_generating_data();
\&  is_deeply_snapshot $got, \*(Aqtest description\*(Aq; # could also be in a subtest
\&
\&  # command line:
\&  TEST_SNAPSHOT_UPDATE=1 prove \-lr t
\&  # or
\&  TEST_SNAPSHOT_UPDATE=1 make test
\&  # if your code means the expected data should change, then inspect with
\&  git diff \-w
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Not connected with Test::Snapshots, which is based on a similar
concept but for running executables.
.PP
Implements a function to automate the storing and updating of expected
test outputs. This is based on the idea known in frontend development
circles as \*(L"snapshot testing\*(R", hence the module name.
.PP
These snapshots will be stored in files whose names are automatically
generated from:
.ie n .IP "the test filename ($0)" 4
.el .IP "the test filename (\f(CW$0\fR)" 4
.IX Item "the test filename ($0)"
.PD 0
.IP "any subtests' names surrounding and including this one" 4
.IX Item "any subtests' names surrounding and including this one"
.IP "the test description if any" 4
.IX Item "the test description if any"
.PD
.PP
If that file is not present, it will be treated as though it contains
an \f(CW\*(C`undef\*(C'\fR.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.SS "is_deeply_snapshot"
.IX Subsection "is_deeply_snapshot"
Exported by default. Takes two mandatory arguments:
.IP "\(bu" 4
The \*(L"got\*(R" data (mandatory), a scalar which might be a reference. It will
be passed to \*(L"is_deeply\*(R" in Test::More to be compared to the snapshotted
data.
.IP "\(bu" 4
A text description of this test (mandatory). It will be used for reporting
results, but also to derive the filename in which the \*(L"expected\*(R" data
is stored.
.PP
Will return the truth value of whether the test passed this time \-
see below for automatic updating of \*(L"expected\*(R" data.
.SH "ENVIRONMENT"
.IX Header "ENVIRONMENT"
To have this module automatically update its \*(L"expected\*(R" data, set
environment variable \f(CW\*(C`TEST_SNAPSHOT_UPDATE\*(C'\fR to a true value. If the
got and expected data do not match, a test failure will be reported,
but the \*(L"expected\*(R" data will be updated anyway.
.PP
This means it is safe to always have the variable set to a true value,
so long as you are using source control (you \fIare\fR using source control,
right?) and check your diffs before committing.
.SH "FILE FORMAT"
.IX Header "FILE FORMAT"
The \*(L"expected\*(R" data will be stored in a format generated by
\&\*(L"Dumper\*(R" in Data::Dumper, with these values set to true, to maximise
readability (and to minimise diffs) of the stored data:
.IP "Sortkeys" 4
.IX Item "Sortkeys"
.PD 0
.IP "Indent" 4
.IX Item "Indent"
.IP "Terse" 4
.IX Item "Terse"
.PD
.SH "AUTHOR"
.IX Header "AUTHOR"
Ed J, \f(CW\*(C`<etj at cpan.org>\*(C'\fR
.SH "LICENSE"
.IX Header "LICENSE"
Copyright (C) Ed J
.PP
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.