make warning assertion more robust

Signed-off-by: Jinzhe Zeng <[email protected]>

tests/analysis/elasticity/test_elastic.py

@@ -182,7 +182,7 @@ def test_new(self):
             UserWarning, match="Input elastic tensor does not satisfy standard Voigt symmetries"
         ) as warns:
             ElasticTensor(non_symm)
-        assert len(warns) == 1
+        assert sum("Input elastic tensor does not satisfy standard Voigt symmetries" in str(warn) for warn in warns) == 1
 
         bad_tensor1 = np.zeros((3, 3, 3))
         bad_tensor2 = np.zeros((3, 3, 3, 2))
@@ -220,7 +220,8 @@ def test_from_independent_strains(self):
         stresses = self.toec_dict["stresses"]
         with pytest.warns(UserWarning, match="No eq state found, returning zero voigt stress") as warns:
             et = ElasticTensor.from_independent_strains(strains, stresses)
-        assert len(warns) == 2
+        assert sum("No eq state found" in str(warn) for warn in warns) == 1
+        assert sum("Extra strain states in strain-" in str(warn) for warn in warns) == 1
         assert_allclose(et.voigt, self.toec_dict["C2_raw"], atol=1e1)
 
     def test_energy_density(self):