Raise on histogram le lables of any accepted type (#192)

Author: NelsonVides

src/metrics/prometheus_histogram.erl

@@ -525,8 +525,12 @@ validate_histogram_spec(Spec) ->
 validate_histogram_labels(Labels) ->
     [raise_error_if_le_label_found(Label) || Label <- Labels].
 
+raise_error_if_le_label_found(le) ->
+    erlang:error({invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""});
 raise_error_if_le_label_found("le") ->
     erlang:error({invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""});
+raise_error_if_le_label_found(<<"le">>) ->
+    erlang:error({invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""});
 raise_error_if_le_label_found(Label) ->
     Label.
 

test/eunit/metric/prometheus_histogram_tests.erl

@@ -84,6 +84,14 @@ test_errors(_) ->
             {invalid_metric_labels, 12, "not list"},
             prometheus_histogram:new([{name, "qwe"}, {labels, 12}, {help, ""}])
         ),
+        ?_assertError(
+            {invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""},
+            prometheus_histogram:new([
+                {name, "qwe"},
+                {labels, ["qwe", le]},
+                {help, ""}
+            ])
+        ),
         ?_assertError(
             {invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""},
             prometheus_histogram:new([
@@ -92,6 +100,14 @@ test_errors(_) ->
                 {help, ""}
             ])
         ),
+        ?_assertError(
+            {invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""},
+            prometheus_histogram:new([
+                {name, "qwe"},
+                {labels, ["qwe", <<"le">>]},
+                {help, ""}
+            ])
+        ),
         ?_assertError(
             {invalid_metric_help, 12, "metric help is not a string"},
             prometheus_histogram:new([{name, "qwe"}, {help, 12}])