Add test for add_custom_scalar (#449)

* add test for custom_scalars

* only do smoke test

tests/expect/test_summary.test_custom_scalars.expect

@@ -0,0 +1,14 @@
+value {
+  tag: "custom_scalars__config__"
+  tensor {
+    dtype: DT_STRING
+    tensor_shape {
+    }
+    string_val: "\022(\n\006Taiwan\022\036\n\004twse\022\026\n\ttwse/0050\n\ttwse/2330\022]\n\003USA\022$\n\003dow\032\035\n\033\n\007dow/aaa\022\007dow/bbb\032\007dow/ccc\0220\n\006nasdaq\032&\n$\n\nnasdaq/aaa\022\nnasdaq/bbb\032\nnasdaq/ccc"
+  }
+  metadata {
+    plugin_data {
+      plugin_name: "custom_scalars"
+    }
+  }
+}

tests/test_summary.py

@@ -79,6 +79,12 @@ def test_histogram_fd(self):
     def test_histogram_doane(self):
         compare_proto(summary.histogram('dummy', tensor_N(shape=(1024,)), bins='doane', max_bins=5), self)
 
+    def test_custom_scalars(self):
+        layout = {'Taiwan': {'twse': ['Multiline', ['twse/0050', 'twse/2330']]},
+                    'USA': {'dow': ['Margin', ['dow/aaa', 'dow/bbb', 'dow/ccc']],
+                            'nasdaq': ['Margin', ['nasdaq/aaa', 'nasdaq/bbb', 'nasdaq/ccc']]}}
+        summary.custom_scalars(layout)  # smoke test only.
+
     def test_mesh(self):
         vertices_tensor = np.array([[
             [1, 1, 1],