Implement persistent optional tag

src/sage/doctest/parsing.py

@@ -109,6 +109,8 @@ def parse_optional_tags(string):
         ['bar', 'foo']
         sage: parse_optional_tags("sage: #optional -- foo.bar, baz")
         {'foo.bar'}
+        sage: parse_optional_tags("sage: #needs foo.bar, baz")
+        {'foo.bar'}
         sage: sorted(list(parse_optional_tags("    sage: factor(10^(10^10) + 1) # LoNg TiME, NoT TeSTED; OptioNAL -- P4cka9e")))
         ['long time', 'not tested', 'p4cka9e']
         sage: parse_optional_tags("    sage: raise RuntimeError # known bug")
@@ -137,17 +139,18 @@ def parse_optional_tags(string):
     # strip_string_literals replaces comments
     comment = "#" + (literals[comment]).lower()
 
-    optional_regex = re.compile(r'(arb216|arb218|py2|long time|not implemented|not tested|known bug)|([^ a-z]\s*optional\s*[:-]*((\s|\w|[.])*))')
+    optional_regex = re.compile(r'arb216|arb218|py2|long time|not implemented|not tested|known bug'
+                                r'|[^ a-z]\s*(optional|needs)\s*[:-]*((?:\s|\w|[.])*)')
 
     tags = []
     for m in optional_regex.finditer(comment):
-        cmd = m.group(1)
+        cmd = m.group(0)
         if cmd == 'known bug':
             tags.append('bug')  # so that such tests will be run by sage -t ... -only-optional=bug
+        elif m.group(1) is not None:
+            tags.extend(m.group(2).split() or [""])
         elif cmd:
             tags.append(cmd)
-        else:
-            tags.extend(m.group(3).split() or [""])
     return set(tags)
 
 
@@ -522,7 +525,7 @@ def parse(self, string, *args):
 
         - A list consisting of strings and :class:`doctest.Example`
           instances.  There will be at least one string between
-          successive examples (exactly one unless or long or optional
+          successive examples (exactly one unless long or optional
           tests are removed), and it will begin and end with a string.
 
         EXAMPLES::
@@ -571,7 +574,7 @@ def parse(self, string, *args):
         of the current line should be joined to the next line.  This
         feature allows for breaking large integers over multiple lines
         but is not standard for Python doctesting.  It's not
-        guaranteed to persist, but works in Sage 5.5::
+        guaranteed to persist::
 
             sage: n = 1234\
             ....:     5678
@@ -587,6 +590,23 @@ def parse(self, string, *args):
             sage: print(m)
             87654321
 
+        Optional tags at the start of an example block persist to the end of
+        the block (delimited by a blank line)::
+
+            sage: # needs sage.rings.number_field, long time
+            sage: QQbar(I)^10000
+            1
+            sage: QQbar(I)^10000  # not tested
+            I
+
+            sage: # needs sage.rings.finite_rings
+            sage: GF(7)
+            Finite Field of size 7
+            sage: GF(10)
+            Traceback (most recent call last):
+            ...
+            ValueError: the order of a finite field must be a prime power
+
         Test that :trac:`26575` is resolved::
 
             sage: example3 = 'sage: Zp(5,4,print_mode="digits")(5)\n...00010'
@@ -630,9 +650,14 @@ def parse(self, string, *args):
         string = find_sage_continuation.sub(r"\1...", string)
         res = doctest.DocTestParser.parse(self, string, *args)
         filtered = []
+        persistent_optional_tags = []
         for item in res:
             if isinstance(item, doctest.Example):
                 optional_tags = parse_optional_tags(item.source)
+                if item.source.startswith("sage: ") and item.source[6:].lstrip().startswith('#'):
+                    persistent_optional_tags = optional_tags
+                    continue
+                optional_tags = optional_tags.union(persistent_optional_tags)
                 if optional_tags:
                     for tag in optional_tags:
                         self.optionals[tag] += 1
@@ -654,6 +679,7 @@ def parse(self, string, *args):
                 elif self.optional_only:
                     self.optionals['sage'] += 1
                     continue
+
                 if replace_ellipsis:
                     item.want = item.want.replace(ellipsis_tag, "...")
                     if item.exc_msg is not None:
@@ -664,6 +690,9 @@ def parse(self, string, *args):
                     if item.sage_source.lstrip().startswith('#'):
                         continue
                     item.source = preparse(item.sage_source)
+            else:
+                if item == '\n':
+                    persistent_optional_tags = []
             filtered.append(item)
         return filtered
 

src/sage/dynamics/arithmetic_dynamics/projective_ds.py

@@ -5979,7 +5979,7 @@ def reduced_form(self, **kwds):
             sage: f = DynamicalSystem_projective([x^3 + x*y^2, y^3])
             sage: m = matrix(QQ, 2, 2, [-201221, -1, 1, 0])
             sage: f = f.conjugate(m)
-            sage: f.reduced_form(prec=50, smallest_coeffs=False) #needs 2 periodic
+            sage: f.reduced_form(prec=50, smallest_coeffs=False) # this needs 2 periodic
             Traceback (most recent call last):
             ...
             ValueError: accuracy of Newton's root not within tolerance(0.000066... > 1e-06), increase precision
@@ -5997,7 +5997,7 @@ def reduced_form(self, **kwds):
         ::
 
             sage: PS.<x,y> = ProjectiveSpace(ZZ, 1)
-            sage: f = DynamicalSystem_projective([x^2+ x*y, y^2]) #needs 3 periodic
+            sage: f = DynamicalSystem_projective([x^2+ x*y, y^2]) # this needs 3 periodic
             sage: m = matrix(QQ, 2, 2, [-221, -1, 1, 0])
             sage: f = f.conjugate(m)
             sage: f.reduced_form(prec=200, smallest_coeffs=False)