Smoke tests (#604)

smoke tests

client/src/components/brushableHistogram/index.js

@@ -237,6 +237,7 @@ class HistogramBrush extends React.Component {
     d3.select(svgRef)
       .append("g")
       .attr("class", "brush")
+      .attr("data-testid", `${svgRef.id}-brush`)
       .call(
         d3
           .brushX()
@@ -281,6 +282,8 @@ class HistogramBrush extends React.Component {
     return (
       <div
         id={`histogram_${field}`}
+        data-testid={`histogram-${field}`}
+        data-testclass={isDiffExp ? `histogram-diffexp` : ""}
         style={{
           padding: globals.leftSidebarSectionPadding,
           backgroundColor: zebra ? globals.lightestGrey : "white"