Implement specified timeout for slow doctests

src/sage/doctest/forker.py

@@ -518,6 +518,54 @@ def getvalue(self):
 TestResults = namedtuple('TestResults', 'failed attempted')
 
 
+def _parse_example_timeout(source: str, default_timeout: float) -> float:
+    """
+    Parse the timeout value from a doctest example's source.
+
+    INPUT:
+
+    - ``source`` -- the source code of a ``doctest.Example``
+    - ``default_timeout`` -- the default timeout value to use
+
+    OUTPUT:
+
+    - a float, the timeout value to use for the example
+
+    TESTS::
+
+        sage: from sage.doctest.forker import _parse_example_timeout
+        sage: _parse_example_timeout("sleep(10)  # long time (limit 10s)", 5.0r)
+        10.0
+        sage: _parse_example_timeout("sleep(10)  # long time (limit 10s, possible regression)", 5.0r)
+        10.0
+        sage: _parse_example_timeout("sleep(10)  # long time (20s)", 5.0r)
+        5.0
+        sage: _parse_example_timeout("sleep(10)  # long time (limit 1a2s)", 5.0r)
+        Traceback (most recent call last):
+        ...
+        ValueError: malformed optional tag '# long time (limit 1a2s)', should be '# long time (limit <number>s)'
+        sage: _parse_example_timeout("sleep(10)  # long time (:issue:`12345`)", 5.0r)
+        5.0
+    """
+    # TODO this double-parsing is inefficient, should make :meth:`SageDocTestParser.parse`
+    # return subclass of doctest.Example that already include the timeout value
+    from sage.doctest.parsing import parse_optional_tags
+    value = parse_optional_tags(source).get("long time", None)
+    if value is None:
+        # either has the "long time" tag without any value in parentheses,
+        # or tag not present
+        return default_timeout
+    assert isinstance(value, str)
+    match = re.fullmatch(r'\s*limit\s+(\S+)s(\s*,.*)?', value.strip())
+    if match:
+        try:
+            return float(match[1])
+        except ValueError:
+            raise ValueError(f"malformed optional tag '# long time ({value})', should be '# long time (limit <number>s)'")
+    else:
+        return default_timeout
+
+
 class SageDocTestRunner(doctest.DocTestRunner):
     def __init__(self, *args, **kwds):
         """
@@ -820,8 +868,10 @@ def compiler(example):
             if example.warnings:
                 for warning in example.warnings:
                     out(self._failure_header(test, example, f'Warning: {warning}'))
+
             if outcome is SUCCESS:
-                if self.options.warn_long > 0 and example.cputime + check_timer.cputime > self.options.warn_long:
+                if self.options.warn_long > 0 and example.cputime + check_timer.cputime > _parse_example_timeout(
+                        example.source, self.options.warn_long):
                     self.report_overtime(out, test, example, got,
                                          check_timer=check_timer)
                 elif example.warnings:
@@ -2157,7 +2207,7 @@ def dispatch(self):
             sage: DC.reporter = DR
             sage: DC.dispatcher = DD
             sage: DC.timer = Timer().start()
-            sage: DD.dispatch()
+            sage: DD.dispatch()  # long time (limit 20s)
             sage -t .../sage/modules/free_module_homspace.py
                 [... tests, ...s wall]
             sage -t .../sage/rings/big_oh.py

src/sage/interacts/test_jupyter.rst

@@ -205,7 +205,7 @@
     Exact value of the integral \(\displaystyle\int_{0}^{2}x^{2} +
     1\,\mathrm{d}x=4.666666666666668\)
 
-    sage: test(interacts.calculus.function_tool)  # long time
+    sage: test(interacts.calculus.function_tool)
     ...Interactive function <function function_tool at ...> with 7 widgets
       f: EvalText(value='sin(x)', description='f')
       g: EvalText(value='cos(x)', description='g')

src/sage/interfaces/maxima_abstract.py

@@ -304,7 +304,7 @@
         EXAMPLES::
 
             # The output is kind of random
-            sage: sorted(maxima._commands(verbose=False))
+            sage: sorted(maxima._commands(verbose=False))  # long time (limit 40s)
             [...
              'display',
              ...
@@ -337,7 +337,7 @@
 
         EXAMPLES::
 
             sage: t = maxima._tab_completion(verbose=False)
             sage: 'gcd' in t
             True
             sage: len(t)    # random output

src/sage/rings/semirings/tropical_mpolynomial.py

@@ -543,12 +543,13 @@ def dual_subdivision(self):
 
         A subdivision with many faces, not all of which are triangles::
 
+            sage: # long time
             sage: T = TropicalSemiring(QQ)
             sage: R.<x,y> = PolynomialRing(T)
             sage: p3 = (R(8) + R(4)*x + R(2)*y + R(1)*x^2 + x*y + R(1)*y^2
             ....:      + R(2)*x^3 + x^2*y + x*y^2 + R(4)*y^3 + R(8)*x^4
             ....:      + R(4)*x^3*y + x^2*y^2 + R(2)*x*y^3 + y^4)
-            sage: pc = p3.dual_subdivision(); pc
+            sage: pc = p3.dual_subdivision(); pc  # long time (limit 40s)
             Polyhedral complex with 10 maximal cells
             sage: [p.Vrepresentation() for p in pc.maximal_cells_sorted()]
             [(A vertex at (0, 0), A vertex at (0, 1), A vertex at (1, 0)),

src/sage/schemes/elliptic_curves/ell_generic.py

@@ -2476,6 +2476,8 @@ def multiplication_by_m(self, m, x_only=False):
             sage: assert(E(eval(f,P)) == 2*P)
 
         The following test shows that :issue:`6413` is fixed for elliptic curves over finite fields::
+
+            sage: # long time
             sage: p = 7
             sage: K.<a> = GF(p^2)
             sage: E = EllipticCurve(K, [a + 3, 5 - a])

src/sage/stats/distributions/discrete_gaussian_lattice.py

@@ -504,7 +504,7 @@ def __init__(self, B, sigma=1, c=0, r=None, precision=None, sigma_basis=False):
             ....:     add_samples(1000)
             sage: sum(counter.values())  # random
             3000
-            sage: while abs(m*f(v)*1.0/nf/counter[v] - 1.0) >= 0.1:                     # needs sage.symbolic
+            sage: while abs(m*f(v)*1.0/nf/counter[v] - 1.0) >= 0.1:                     # needs sage.symbolic  # long time (limit 20s)
             ....:     add_samples(1000)
 
         If the covariance provided is not positive definite, an error is thrown::

src/sage/symbolic/expression.pyx

@@ -13221,7 +13221,7 @@ cdef class Expression(Expression_abc):
         answer::
 
             sage: f = ln(1+4/5*sin(x))
-            sage: integrate(f, x, -3.1415, 3.1415)  # random
+            sage: integrate(f, x, -3.1415, 3.1415)  # random  # long time (limit 10s)
             integrate(log(4/5*sin(x) + 1), x, -3.14150000000000,
             3.14150000000000)
             sage: # needs sage.libs.giac