test: add realtime price to top level

bats/core/api/public.bats

@@ -53,3 +53,17 @@ load "../../helpers/subscriber.bash"
 
   stop_subscriber
 }
+
+@test "public: can subscribe to realtime price" {
+  subscribe_to 'anon' real-time-price-sub '{"currency": "EUR"}'
+  retry 10 1 grep 'Data.*\brealtimePrice\b.*EUR' "${SUBSCRIBER_LOG_FILE}"
+
+  num_errors=$(
+    grep 'Data.*\brealtimePrice\b.*EUR' "${SUBSCRIBER_LOG_FILE}" \
+      | awk '{print $2}' \
+      | jq -r '.data.brealtimePrice.errors | length'
+  )
+  [[ "$num_errors" == "0" ]] || exit 1
+
+  stop_subscriber
+}

bats/gql/real-time-price-sub.gql

@@ -0,0 +1,22 @@
+subscription realtimePrice($currency: DisplayCurrency!) {
+  realtimePrice(input: { currency: $currency }) {
+    errors {
+      message
+    }
+    realtimePrice {
+      id
+      timestamp
+      denominatorCurrency
+      btcSatPrice {
+        base
+        offset
+        currencyUnit
+      }
+      usdCentPrice {
+        base
+        offset
+        currencyUnit
+      }
+    }
+  }
+}

bats/helpers/subscriber.bash

@@ -3,8 +3,10 @@ source "$(dirname "$CURRENT_FILE")/_common.bash"
 
 export SUBSCRIBER_PID_FILE="${BATS_ROOT_DIR}/.gql_subscriber_pid"
 export SUBSCRIBER_LOG_FILE="${BATS_ROOT_DIR}/.e2e-subscriber.log"
+
 subscribe_to() {
   stop_subscriber > /dev/null 2>&1 || true
+  rm -f "$SUBSCRIBER_LOG_FILE" "$SUBSCRIBER_PID_FILE" || true
 
   token_name=$1
   if [[ -n "$token_name" && "$token_name" != 'anon' ]]; then