MINOR, WIP remove warning for custom solvers in rERP (mne-tools#5437)

* init

* specify test

mne/stats/regression.py

@@ -253,11 +253,7 @@ def solver(X, y):
                 return linalg.solve(a, X.T * y, sym_pos=True,
                                     overwrite_a=True, overwrite_b=True).T
     elif callable(solver):
-        warn("When using a custom solver, note that since MNE 0.15, this "
-             "function will pass the transposed data (n_channels, n_times) "
-             "to the solver. If you are using a solver that expects a "
-             "different format, it will give wrong results and might in "
-             "extreme cases crash your session.")
+        pass
     else:
         raise TypeError("The solver must be a str or a callable.")
 

mne/stats/tests/test_regression.py

@@ -140,18 +140,15 @@ def test_continuous_regression_with_overlap():
     from sklearn.linear_model.ridge import ridge_regression
 
     def solver(X, y):
-        return ridge_regression(X, y, alpha=0.)
-
-    with pytest.warns(RuntimeWarning, match='transposed'):
-        assert_allclose(effect, linear_regression_raw(
-            raw, events, tmin=0, solver=solver)['1'].data.flatten())
+        return ridge_regression(X, y, alpha=0., solver="cholesky")
+    assert_allclose(effect, linear_regression_raw(
+        raw, events, tmin=0, solver=solver)['1'].data.flatten())
 
     # test bad solvers
     def solT(X, y):
-        return ridge_regression(X, y, alpha=0.).T
-    with pytest.warns(RuntimeWarning, match='transposed'):
-        pytest.raises(ValueError, linear_regression_raw, raw, events,
-                      solver=solT)
+        return ridge_regression(X, y, alpha=0., solver="cholesky").T
+    pytest.raises(ValueError, linear_regression_raw, raw, events,
+                  solver=solT)
     pytest.raises(ValueError, linear_regression_raw, raw, events, solver='err')
     pytest.raises(TypeError, linear_regression_raw, raw, events, solver=0)