tests/heredoc.scm: Add test for (enable-syntax) macro

Test both compiled and non-compiled variants of the test in order to
stress the scenarios of *when* the read-macro is set.

Also change the (eval-when ...) case used:
- "compile": for when the code is being compiled only, and before its
  execution;
- "eval": for the the code is being evaluated only, during its
  execution.

Also from the Guile manual (via 'info (guile)Loading'):

    Changing ‘current-reader’ is typically useful to introduce local
    syntactic changes, such that code following the ‘fluid-set!’ call
    is read using the newly installed reader.  The ‘current-reader’
    change should take place at evaluation time when the code is
    evaluated, or at compilation time when the code is compiled:

         (eval-when (compile eval)
           (fluid-set! current-reader my-own-reader))

    The ‘eval-when’ form above ensures that the ‘current-reader’ change
    occurs at the right time.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/xyz/euandreh/heredoc.scm b/src/xyz/euandreh/heredoc.scm
index ba7b727..a7b969d 100644
--- a/src/xyz/euandreh/heredoc.scm
+++ b/src/xyz/euandreh/heredoc.scm
@@ -98,5 +98,5 @@
           s)))))
 
 (define-macro (enable-syntax)
-  `(eval-when (expand load eval)
+  `(eval-when (compile eval)
      (read-hash-extend #\" (@ (xyz euandreh heredoc) reader))))