Rewrites user example compilation test

Now everything is compiled via -c, instead of using EVAL. This is
slower, but closes #2764 since apparently the evaluation of so much
code was gobbling up memory, and closes #2782 since either the memory
itself or the creation of multiple objects was affecting this
somehow. It also causes #2789, so some changes are trying to fix that.

Author: JJ

doc/Language/testing.pod6

@@ -9,17 +9,17 @@ Testing code is an integral part of software development. Tests provide
 automated, repeatable verifications of code behavior, and ensures your
 code works as expected.
 
-In Perl 6, the L<Test|/type/Test> module provides a testing framework, used also by
-Perl 6's official spectest suite.
+In Perl 6, the L<Test|/type/Test> module provides a testing framework, used also
+by Perl 6's official spectest suite.
 
 The testing functions emit output conforming to the L<Test Anything Protocol|https://testanything.org>. In general, they are used in sink context:
 
-=for code :preamble<my ($meta,$relaxed-name); sub check-name($meta,:$relaxed-name){}>
+=for code :preamble<use Test; my ($meta,$relaxed-name); sub check-name($meta,:$relaxed-name){}>
 ok check-name($meta, :$relaxed-name), "name has a hyphen rather than '::'"
 
 but all functions also return as a Boolean if the test has been successful or not, which can be used to print a message if the test fails:
 
-=begin code :preamble<my ($meta,$relaxed-name); sub check-name($meta,:$relaxed-name){}>
+=begin code :preamble<use Test; my ($meta,$relaxed-name); sub check-name($meta,:$relaxed-name){}>
 ok check-name($meta, :$relaxed-name), "name has a hyphen rather than '::'" \
   or diag "\nTo use hyphen in name, pass :relaxed-name to meta-ok\n";
 =end code

doc/Type/Test.pod6

@@ -20,7 +20,8 @@ Defined as:
 Specify the count of tests -- usually written at the beginning of a
 test file.
 
-    plan 15;   # expect to run 15 tests
+=for code :preamble<use Test;>
+plan 15;   # expect to run 15 tests
 
 In C<subtest>s, C<plan> is used to specify the count of tests within
 the subtest.
@@ -76,11 +77,11 @@ a C<plan> function when all tests are finalized. Use of C<plan> can help detect
 test failures otherwise not reported because tests were accidentally skipped due
 to bugs in the tests or bugs in the compiler. For example:
 
+=for code :preamble<use Test;>
     sub do-stuff {@};
     use Test;
     ok .is-prime for do-stuff;
     done-testing;
-
     # output:
     1..0
 
@@ -91,11 +92,11 @@ passes.
 
 Adding C<plan> gives a true picture of the test:
 
+=for code :preamble<use Test;>
     sub do-stuff {@};
     use Test;
     plan 1;
     ok .is-prime for do-stuff;
-
     # output:
     1..1
     # Looks like you planned 1 test, but ran 0
@@ -114,13 +115,15 @@ C<True>. The C<nok> function marks a test as passed if the given value evaluates
 to C<False>. Both functions accept an optional description of the test as second
 parameter.
 
+=for code :preamble<use Test;>
     my $response; my $query; ...;
     ok  $response.success, 'HTTP response was successful';
     nok $query.error,      'Query completed without error';
 
 In principle, you could use C<ok> for every kind of comparison test, by
 including the comparison in the expression passed to C<$value>:
 
+=for code :preamble<use Test;>
     sub factorial($x) { ... };
     ok factorial(6) == 720, 'Factorial - small integer';
 
@@ -138,6 +141,7 @@ The C<nok> function marks a test as passed if the given value evaluates to
 C<False>. It also accepts an optional description of the test as second
 argument.
 
+=for code :preamble<use Test;>
     my $response; my $query; ...;
     ok  $response.success, 'HTTP response was successful';
     nok $query.error,      'Query completed without error';
@@ -161,6 +165,7 @@ a good function for testing more complex things, such as lists: C<is (1, (2,
 different. For those cases, use
 L«C<is-deeply> routine|/language/testing#index-entry-is-deeply-is-deeply($value,_$expected,_$description?)»
 
+=for code :preamble<use Test;>
     my $pdf-document; sub factorial($x) { ... }; ...;
     is $pdf-document.author, "Joe", 'Retrieving the author field';
     is factorial(6),         720,   'Factorial - small integer';
@@ -172,7 +177,7 @@ failure message differently, to show the whitespace in each values. For example,
 in the output below, the second test shows the literal C<\t> in the C<got:>
 line:
 
-=for code
+=for code :preamble<use Test;>
 is "foo\tbar", "foo\tbaz";   # expected: 'foo     baz'␤#      got: 'foo   bar'
 is "foo\tbar", "foo    bar"; # expected: "foo    bar"␤#      got: "foo\tbar"
 
@@ -187,8 +192,8 @@ Marks a test as passed if C<$value> and C<$expected> are B<not> equal using
 the same rules as C<is()>.  The function accepts an optional description
 of the test.
 
+=for code :preamble<use Test;>
     isnt pi, 3, 'The constant π is not equal to 3';
-
     my Int $a = 23;
     $a = Nil;
     isnt $a, Nil, 'Nil should not survive being put in a container';
@@ -245,6 +250,8 @@ If no tolerance is set, the function will base the tolerance on the I<absolute>
 value of C<$expected>: if it's smaller than C<1e-6>, use absolute tolerance of
 C<1e-5>; if it's larger, use relative tolerance of C<1e-6>.
 
+=begin code :preamble<use Test;>
+
     my Numeric ($value, $expected, $abs-tol, $rel-tol) = ...
 
     is-approx $value, $expected;
@@ -261,18 +268,22 @@ C<1e-5>; if it's larger, use relative tolerance of C<1e-6>.
 
     is-approx $value, $expected, :$abs-tol, :$rel-tol;
     is-approx $value, $expected, :$abs-tol, :$rel-tol, 'test description';
+=end code
 
 =head3 Absolute tolerance
 
 When an absolute tolerance is set, it's used as the actual maximum value by
 which the C<$value> and C<$expected> can differ. For example:
 
+=begin code :preamble<use Test;>
+
     is-approx 3, 4, 2; # success
     is-approx 3, 6, 2; # fail
 
     is-approx 300, 302, 2; # success
     is-approx 300, 400, 2; # fail
     is-approx 300, 600, 2; # fail
+=end code
 
 Regardless of values given, the difference between them cannot be more
 than C<2>.
@@ -285,11 +296,13 @@ larger the value they can differ by can be.
 
 For example:
 
+=begin code :preamble<use Test;>
     is-approx 10, 10.5, :rel-tol<0.1>; # success
     is-approx 10, 11.5, :rel-tol<0.1>; # fail
 
     is-approx 100, 105, :rel-tol<0.1>; # success
     is-approx 100, 115, :rel-tol<0.1>; # fail
+=end code
 
 Both versions use C<0.1> for relative tolerance, yet the first can differ
 by about C<1> while the second can differ by about C<10>. The function used
@@ -305,7 +318,7 @@ and the test will fail if C<rel-diff> is higher than C<$rel-tol>.
 
 =head3 Both absolute and relative tolerance specified
 
-=for code :skip-test<compile time error>
+=for code :preamble<use Test; my ($value, $expected);>
 is-approx $value, $expected, :rel-tol<.5>, :abs-tol<10>;
 
 When both absolute and relative tolerances are specified, each will be
@@ -375,18 +388,20 @@ The C<$comparison> comparator can be either a L<Callable|/type/Callable> or
 a L<Str|/type/Str> containing an infix operator, such as C<'=='>, a C<'~~'>, or a
 user-defined infix.
 
+=for code :preamble<use Test;>
     cmp-ok 'my spelling is apperling', '~~', /perl/, "bad speller";
 
-Metaoperators cannot be given as a string; pass them as a L<Callable|/type/Callable>
-instead:
+Metaoperators cannot be given as a string; pass them as a
+L<Callable|/type/Callable> instead:
 
+=for code :preamble<use Test;>
     cmp-ok <a b c>, &[!eqv], <b d e>, 'not equal';
 
 A L<Callable|/type/Callable> C<$comparison> lets you use custom comparisons:
 
+=for code :preamble<use Test;>
     sub my-comp { $^a / $^b  < rand };
     cmp-ok 1, &my-comp, 2, 'the dice giveth and the dice taketh away'
-
     cmp-ok 2, -> $a, $b { $a.is-prime and $b.is-prime and $a < $b }, 7,
         'we got primes, one larger than the other!';
 
@@ -401,12 +416,14 @@ given C<$expected-type>.  For convenience, types may also be specified as a
 string.  The function accepts an optional description of the test, which
 defaults to a string that describes the object.
 
+=begin code :preamble<use Test;>
     class Womble {}
     class GreatUncleBulgaria is Womble {}
     my $womble = GreatUncleBulgaria.new;
 
     isa-ok $womble, Womble, "Great Uncle Bulgaria is a womble";
     isa-ok $womble, 'Womble';     # equivalent
+=end code
 
 =head2 sub can-ok
 
@@ -418,6 +435,7 @@ Marks a test as passed if the given C<$variable> can run the given
 C<$method-name>.  The function accepts an optional description.  For
 instance:
 
+=begin code :preamble<use Test;>
     class Womble {};
     my $womble = Womble.new;
 
@@ -428,6 +446,7 @@ instance:
     # with human-generated test description
     can-ok $womble, 'collect-rubbish', "Wombles can collect rubbish";
     #  => Wombles can collect rubbish
+=end code
 
 =head2 sub does-ok
 
@@ -438,6 +457,7 @@ Defined as:
 Marks a test as passed if the given C<$variable> can do the given C<$role>.
 The function accepts an optional description of the test.
 
+=begin code :preamble<use Test;>
     # create a Womble who can invent
     role Invent {
         method brainstorm { say "Aha!" }
@@ -456,7 +476,7 @@ The function accepts an optional description of the test.
 
     does-ok $tobermory, Invent, "Tobermory can invent";
     #  => Tobermory can invent
-
+=end code
 
 =head2 sub like
 
@@ -466,6 +486,7 @@ Defined as:
 
 Use it this way:
 
+=for code :preamble<use Test;>
     like 'foo', /fo/, 'foo looks like fo';
 
 Marks a test as passed if the C<$value>, when coerced to a string, matches the
@@ -480,6 +501,7 @@ Defined as:
 
 Used this way:
 
+=for code :preamble<use Test;>
     unlike 'foo', /bar/, 'foo does not look like bar';
 
 Marks a test as passed if the C<$value>, when coerced to a string, does B<not>
@@ -494,6 +516,7 @@ Defined as:
 
 Marks a test as passed if the given C<$module> loads correctly.
 
+=for code :preamble<use Test;>
     use-ok 'Full::Qualified::ModuleName';
 
 =head2 sub dies-ok
@@ -506,7 +529,7 @@ Marks a test as passed if the given C<$code> throws an exception.
 
 The function accepts an optional description of the test.
 
-=begin code
+=begin code :preamble<use Test;>
 sub saruman(Bool :$ents-destroy-isengard) {
     die "Killed by Wormtongue" if $ents-destroy-isengard;
 }
@@ -525,7 +548,7 @@ exception.
 
 The function accepts an optional description of the test.
 
-=begin code
+=begin code :preamble<use Test;>
 sub frodo(Bool :$destroys-ring) {
     die "Oops, that wasn't supposed to happen" unless $destroys-ring;
 }
@@ -544,7 +567,7 @@ C<eval>ed as code.
 
 The function accepts an optional description of the test.
 
-=begin code
+=begin code :preamble<use Test;>
 eval-dies-ok q[my $joffrey = "nasty";
                die "bye bye Ned" if $joffrey ~~ /nasty/],
     "Ned Stark dies";
@@ -561,7 +584,7 @@ exception when C<eval>ed as code.
 
 The function accepts an optional description of the test.
 
-=begin code
+=begin code :preamble<use Test;>
 eval-lives-ok q[my $daenerys-burns = False;
                 die "Oops, Khaleesi now ashes" if $daenerys-burns],
     "Dany is blood of the dragon";
@@ -582,7 +605,7 @@ If an exception was thrown, it will also try to match the matcher hash,
 where the key is the name of the method to be called on the exception, and
 the value is the value it should have to pass. For example:
 
-=begin code
+=begin code :preamble<use Test;>
 sub frodo(Bool :$destroys-ring) {
     fail "Oops. Frodo dies" unless $destroys-ring
 };
@@ -598,7 +621,7 @@ the tested code does not sink the possible L<Failures|/type/Failure>. If you
 wish to test that the code returns a L<Failure|/type/Failure> instead of
 throwing, use C<fails-like> routine instead.
 
-=begin code
+=begin code :preamble<use Test;>
 sub fails-not-throws { +"a" }
 # test passes, even though it's just a Failure and would not always throw:
 throws-like { fails-not-throws }, Exception;
@@ -617,14 +640,16 @@ encapsulate your string with a block and an EVAL instead. For instance:
 
 Defined as:
 
-=for code
+=for code :preamble<use Test;>
+
 sub fails-like ( \test where Callable:D|Str:D, $ex-type, $reason?, *%matcher)
 
 Same interface as C<throws-like>, except checks that the code returns a
 L<Failure|/type/Failure> instead of throwing. If the code does throw or if the
 returned L<Failure|/type/Failure> has already been L<handled|/routine/handled>,
 that will be considered as a failed test.
 
+=for code :preamble<use Test;>
     fails-like { +"a" }, X::Str::Numeric,
         :message(/'Cannot convert string to number'/),
     'converting non-numeric string to number fails';
@@ -643,7 +668,7 @@ I<one> test in C<plan>, C<todo>, or C<skip> counts. It will pass the
 test only if B<all> tests in the block pass. The function accepts an
 optional description of the subtest.
 
-=begin code
+=begin code :preamble<use Test;>
 class Womble {}
 
 class GreatUncleBulgaria is Womble {
@@ -665,7 +690,7 @@ You can also place the description as the first positional argument, or use a
 C<Pair> with description as the key and subtest's code as the value. This can be
 useful for subtests with large bodies.
 
-=begin code
+=begin code :preamble<use Test;>
 subtest 'A bunch of tests', {
     plan 42;
     ...
@@ -725,7 +750,7 @@ Skip C<$count> tests, giving a C<$reason> as to why.  By default only one
 test will be skipped.  Use such functionality when a test (or tests) would
 die if run.
 
-=begin code
+=begin code :preamble<use Test;>
 sub num-forward-slashes($arg) { ... } ;
 
 if $*KERNEL ~~ 'linux' {
@@ -750,7 +775,7 @@ Skip the remaining tests.  If the remainder of the tests in the test file
 would all fail due to some condition, use this function to skip them,
 providing an optional C<$reason> as to why.
 
-=begin code
+=begin code :preamble<use Test;>
 my $location; sub womble { ... }; ...;
 unless $location ~~ "Wimbledon Common" {
     skip-rest "We can't womble, the remaining tests will fail";