diff --git a/xdc-plugin/tests/Makefile b/xdc-plugin/tests/Makefile
index e8f8d1b..080f134 100644
--- a/xdc-plugin/tests/Makefile
+++ b/xdc-plugin/tests/Makefile
@@ -19,7 +19,7 @@
 	PART_JSON=xc7a35tcsg324-1.json \
 	OUT_JSON=$(1).json \
 	INPUT_XDC_FILE=$(1).xdc \
-	yosys -p "tcl synth.tcl" $$< -l yosys.log
+	yosys -p "tcl $(1).tcl" $$< -l yosys.log
 
 update_$(1): $(1).json
 	@python compare_output_json.py --json $$< --golden $(1)_golden.json --update
diff --git a/xdc-plugin/tests/synth.tcl b/xdc-plugin/tests/counter.tcl
similarity index 100%
rename from xdc-plugin/tests/synth.tcl
rename to xdc-plugin/tests/counter.tcl
diff --git a/xdc-plugin/tests/port_indexes.tcl b/xdc-plugin/tests/port_indexes.tcl
new file mode 100644
index 0000000..17d3b9e
--- /dev/null
+++ b/xdc-plugin/tests/port_indexes.tcl
@@ -0,0 +1,25 @@
+yosys -import
+plugin -i xdc
+#Import the commands from the plugins to the tcl interpreter
+yosys -import
+
+# -flatten is used to ensure that the output eblif has only one module.
+# Some of symbiflow expects eblifs with only one module.
+synth_xilinx -vpr -flatten -abc9 -nosrl -noclkbuf -nodsp
+
+if {[info procs unknown] != ""} {
+	rename unknown ""
+}
+proc unknown args {puts "'unknown' proc command handler"}
+if {[catch {invalid command}]} {
+	error "Command should be handled by the 'unknown' proc"
+}
+#Read the design constraints
+read_xdc -part_json $::env(PART_JSON) $::env(INPUT_XDC_FILE)
+
+if {[catch {invalid command}]} {
+	error "Command should be handled by the 'unknown' proc"
+}
+
+# Write the design in JSON format.
+write_json $::env(OUT_JSON)