add unittest to check NaN assignment works

since `xt::allclose` does not have a *equal_nan* like `xt::isclose`
(see https://github.com/xtensor-stack/xtensor/issues/1995), the
check is a bit more convoluted than before...

tests/test_probabilist.cpp

@@ -22,7 +22,7 @@ TEST(ProbabilistTests, TestBrier)
     ifs.close();
 
     // compute scores
-    xt::xtensor<double, 2> thresholds = {{690, 534, 445}};
+    xt::xtensor<double, 2> thresholds = {{690, 534, 445, NAN}};
 
     std::vector<xt::xarray<double>> metrics =
             evalhyd::evalp(
@@ -37,27 +37,41 @@ TEST(ProbabilistTests, TestBrier)
     // check results
     // Brier scores
     xt::xtensor<double, 4> bs =
-            {{{{0.10615136, 0.07395622, 0.08669186}}}};
-    EXPECT_TRUE(xt::allclose(metrics[0], bs));
+            {{{{0.10615136, 0.07395622, 0.08669186, NAN}}}};
+    EXPECT_TRUE(
+            xt::sum(xt::isclose(metrics[0], bs, 1e-05, 1e-08, true))
+            == xt::xscalar<double>(4)
+    );
 
     // Brier skill scores
     xt::xtensor<double, 4> bss =
-            {{{{0.5705594, 0.6661165, 0.5635126}}}};
-    EXPECT_TRUE(xt::allclose(metrics[1], bss));
+            {{{{0.5705594, 0.6661165, 0.5635126, NAN}}}};
+    EXPECT_TRUE(
+            xt::sum(xt::isclose(metrics[1], bss, 1e-05, 1e-08, true))
+            == xt::xscalar<double>(4)
+    );
 
     // Brier calibration-refinement decompositions
     xt::xtensor<double, 5> bs_crd =
             {{{{{0.011411758, 0.1524456, 0.2471852},
                 {0.005532413, 0.1530793, 0.2215031},
-                {0.010139431, 0.1220601, 0.1986125}}}}};
-    EXPECT_TRUE(xt::allclose(metrics[2], bs_crd));
+                {0.010139431, 0.1220601, 0.1986125},
+                {NAN, NAN, NAN}}}}};
+    EXPECT_TRUE(
+            xt::sum(xt::isclose(metrics[2], bs_crd, 1e-05, 1e-08, true))
+            == xt::xscalar<double>(12)
+    );
 
     // Brier likelihood-base rate decompositions
     xt::xtensor<double, 5> bs_lbd =
             {{{{{0.012159881, 0.1506234, 0.2446149},
                 {0.008031746, 0.1473869, 0.2133114},
-                {0.017191279, 0.1048221, 0.1743227}}}}};
-    EXPECT_TRUE(xt::allclose(metrics[3], bs_lbd));
+                {0.017191279, 0.1048221, 0.1743227},
+                {NAN, NAN, NAN}}}}};
+    EXPECT_TRUE(
+            xt::sum(xt::isclose(metrics[3], bs_lbd, 1e-05, 1e-08, true))
+            == xt::xscalar<double>(12)
+    );
 }
 
 TEST(ProbabilistTests, TestQuantiles)