Parser: test comments nested in code blocks

See #375.

test/parser/expect/code-block/comment.txt

@@ -0,0 +1,3 @@
+((output (((f.ml (1 0) (2 14)) (code_block  "(* foo *)\
+                                           \nlet bar = ()"))))
+ (warnings ()))

test/parser/expect/code-block/docstring-with-code-block.txt

@@ -0,0 +1,19 @@
+((output
+  (((f.ml (1 0) (1 13)) (code_block "(** {[foo"))
+   ((f.ml (1 14) (2 13))
+    (paragraph
+     (((f.ml (1 14) (1 16)) (word "*)")) ((f.ml (1 16) (2 0)) space)
+      ((f.ml (2 0) (2 3)) (word let)) ((f.ml (2 3) (2 4)) space)
+      ((f.ml (2 4) (2 7)) (word bar)) ((f.ml (2 7) (2 8)) space)
+      ((f.ml (2 8) (2 9)) (word =)) ((f.ml (2 9) (2 10)) space)
+      ((f.ml (2 10) (2 12)) (word "()")) ((f.ml (2 12) (2 13)) (word ])))))
+   ((f.ml (2 13) (2 14)) (paragraph (((f.ml (2 13) (2 14)) (word })))))))
+ (warnings
+  ( "File \"f.ml\", line 1, characters 14-16:\
+   \nParagraph should begin on its own line."
+    "File \"f.ml\", line 2, characters 12-13:\
+   \nUnpaired ']' (end of code).\
+   \nSuggestion: try '\\]'."
+    "File \"f.ml\", line 2, characters 13-14:\
+   \nUnpaired '}' (end of markup).\
+   \nSuggestion: try '\\}'.")))

test/parser/expect/code-block/docstring.txt

@@ -0,0 +1,3 @@
+((output (((f.ml (1 0) (2 14)) (code_block  "(** foo *)\
+                                           \nlet bar = ()"))))
+ (warnings ()))

test/parser/test.ml

@@ -334,6 +334,9 @@ let tests : test_suite list = [
     t "unterminated" "{[foo";
     t "unterminated-bracket" "{[foo]";
     t "trailing-cr" "{[foo\r]}";
+    t "comment" "{[(* foo *)\nlet bar = ()]}";
+    t "docstring" "{[(** foo *)\nlet bar = ()]}";
+    t "docstring-with-code-block" "{[(** {[foo]} *)\nlet bar = ()]}";
   ];
 
   "verbatim", [