diff --git a/test/Dockerfile b/test/Dockerfile
index 19b7c7153..12ea74da5 100644
--- a/test/Dockerfile
+++ b/test/Dockerfile
@@ -42,4 +42,4 @@ COPY --from=vttest /vttest /usr/bin/vttest
 
 COPY ./run.sh /entrypoint.sh
 
-ENTRYPOINT ["/entrypoint.sh"]
+ENTRYPOINT ["/bin/bash"]
diff --git a/test/cases/vttest/1_1.sh.png b/test/cases/vttest/1_1.sh.png
new file mode 100644
index 000000000..ba1bc593d
Binary files /dev/null and b/test/cases/vttest/1_1.sh.png differ
diff --git a/test/run-host.sh b/test/run-host.sh
new file mode 100755
index 000000000..7538c237c
--- /dev/null
+++ b/test/run-host.sh
@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+#
+# This runs a single test case from the host (not from Docker itself). The
+# arguments are the same as run.sh but this wraps it in docker.
+
+docker run \
+  --init \
+  --rm \
+  -v $(pwd):/src \
+  --entrypoint "xvfb-run" \
+  $(docker build -q .) \
+  /entrypoint.sh $@
diff --git a/test/run.sh b/test/run.sh
index 95620f19b..fdfc73768 100755
--- a/test/run.sh
+++ b/test/run.sh
@@ -19,16 +19,21 @@ function has_func() {
 #--------------------------------------------------------------------
 # Flag parsing
 
+ARG_UPDATE=0
 while [[ "$#" -gt 0 ]]; do
     case $1 in
         -e|--exec) ARG_EXEC="$2"; shift ;;
         -c|--case) ARG_CASE="$2"; shift ;;
         -o|--output) ARG_OUT="$2"; shift ;;
+        -u|--update) ARG_UPDATE=1 ;;
         *) echo "Unknown parameter passed: $1"; exit 1 ;;
     esac
     shift
 done
 
+# If we're updating, then just update the file in-place
+if [ "$ARG_UPDATE" -eq 1 ]; then ARG_OUT="${ARG_CASE}.png"; fi
+
 bad=0
 if [ -z "$ARG_EXEC" ]; then bad=1; fi
 if [ -z "$ARG_CASE" ]; then bad=1; fi