Adds preambles closes #2789

doc/Type/Test.pod6

@@ -33,16 +33,17 @@ You can also provide a C<:skip-all> named argument instead of a test count,
 to indicate that you want to skip all of the tests. Such a plan will
 call L«C<exit>|/routine/exit», unless used inside of a C<subtest>.
 
-    plan :skip-all<These tests are only for Windows> unless $*DISTRO.is-win;
-    plan 1;
-    ok dir 'C:/'; # this won't get run on non-Windows
+=for code :preamble<use Test;>
+plan :skip-all<These tests are only for Windows> unless $*DISTRO.is-win;
+plan 1;
+ok dir 'C:/'; # this won't get run on non-Windows
 
 If used in a C<subtest>, it will instead C<return> from that
 C<subtest>'s L«C<Callable>|/type/Callable». For that reason, to be able to
 use C<:skip-all> inside a C<subtest>, you must use a C<sub> instead of a
 regular block:
 
-=begin code
+=begin code :preamble<use Test;>
 plan 2;
 subtest "Some Windows tests" => sub { # <-- note the `sub`; can't use bare block
     plan :skip-all<We aren't on Windows> unless $*DISTRO.is-win;
@@ -634,7 +635,8 @@ Please note that you can only use the string form (for C<EVAL>) if you are not
 referencing any symbols in the surrounding scope. If you are, you should
 encapsulate your string with a block and an EVAL instead. For instance:
 
-    throws-like { EVAL q[ fac("foo") ] }, X::TypeCheck::Argument;
+=for code :preamble<use Test;>
+throws-like { EVAL q[ fac("foo") ] }, X::TypeCheck::Argument;
 
 =head2 sub fails-like
 
@@ -718,11 +720,13 @@ in which case one would C<skip> the test on other platforms.
 Mark C<$count> tests as TODO, giving a C<$reason> as to why.  By default
 only one test will be marked TODO.
 
+=begin code :preamble<use Test;>
     sub my-custom-pi { 3 };
 
     todo 'not yet precise enough';         # Mark the test as TODO.
     is my-custom-pi(), pi, 'my-custom-pi'; # Run the test, but don't report
                                            # failure in test harness.
+=end code
 
 The result from the test code above will be something like:
 
@@ -804,7 +808,7 @@ the test run and mark it as failed.
 If you already know the tests will fail, you can bail out of the test run
 using C<bail-out()>:
 
-=begin code
+=begin code :preamble<use Test;>
 my $has-db-connection;
 ...
 $has-db-connection  or bail-out 'Must have database connection for testing';
@@ -827,9 +831,9 @@ Defined as:
 The C<pass> function marks a test as passed. C<flunk> marks a test as
 B<not> passed. Both functions accept an optional test description.
 
-    pass "Actually, this test has passed";
-
-    flunk "But this one hasn't passed";
+=for code :preamble<use Test;>
+pass "Actually, this test has passed";
+flunk "But this one hasn't passed";
 
 Since these subroutines do not provide indication of what value was received
 and what was expected, they should be used sparingly, such as when evaluating
@@ -851,7 +855,8 @@ provide information that the test itself did not provide.  Or it can be used
 to provide visual markers on how the testing of a test-file is progressing
 (which can be important when doing stress testing).
 
-    diag "Yay!  The tests got to here!";
+=for code :preamble<use Test;>
+diag "Yay!  The tests got to here!";
 
 =end pod