refactor: add host and artifical-delay only if not passed (#3757)

Author: Eric Swanson

e2e/utils/_.bash

@@ -117,19 +117,34 @@ determine_network_directory() {
 # Start the replica in the background.
 dfx_start() {
     local port dfx_config_root webserver_port
-
-    # Start on random port for parallel test execution
-    FRONTEND_HOST="127.0.0.1:0"
+    local args=( "$@" )
+
+    add_default_parameter() {
+        local param_name=$1
+        local param_value=$2
+        local has_param=false
+        for arg in "${args[@]}"; do
+            if [[ $arg == "$param_name" ]]; then
+                has_param=true
+                break
+            fi
+        done
+        if ! $has_param; then
+            args+=( "$param_name" "$param_value" )
+        fi
+    }
+
+    # By default, start on random port for parallel test execution
+    add_default_parameter "--host" "127.0.0.1:0"
+
+    add_default_parameter "--artificial-delay" "100"
 
     determine_network_directory
+
     # Bats creates a FD 3 for test output, but child processes inherit it and Bats will
     # wait for it to close. Because `dfx start` leaves child processes running, we need
     # to close this pipe, otherwise Bats will wait indefinitely.
-    if [[ $# -eq 0 ]]; then
-        dfx start --background --host "$FRONTEND_HOST" --artificial-delay 100 3>&- # Start on random port for parallel test execution
-    else
-        dfx start --background --artificial-delay 100 "$@" 3>&-
-    fi
+    dfx start --background "${args[@]}" 3>&-
 
     dfx_config_root="$E2E_NETWORK_DATA_DIRECTORY/replica-configuration"
     printf "Configuration Root for DFX: %s\n" "${dfx_config_root}"