Update Testing.md

Testing.md

@@ -15,7 +15,9 @@ Additionally, any of the following optional auxilary files and directories may b
 ## Running tests
 
 ```bash
-# Usage: $1 wasmtime <path_to_binary.wasm>
+# Usage: $1 <runtime> <path_to_binary.wasm>
+# $1 wasmtime proc_exit-success.wasm
+# $1 wasmer proc_exit-failure.wasm
 #!/usr/bin/env bash
 
 runtime=$1
@@ -33,13 +35,25 @@ stdout_actual="$output/stdout"
 stderr_actual="$output/stderr"
 status_actual="$output/status"
 
+if [ -e "$prefix.env" ]; then
+  env=$(sed -e 's/^/--env /' < "$input.env")
+else
+  env=""
+fi
+
+if [ -e "$input.dir" ]; then
+  dir="--dir $input.dir"
+else
+  dir=""
+fi
+
 status=0
 
-"$runtime" $input \
-    < "$stdin" \
-    > "$stdout_actual" \
-    2> "$stderr_actual" \
-    || status=$?
+"$runtime" $dir $input \
+  < "$stdin" \
+  > "$stdout_actual" \
+  2> "$stderr_actual" \
+  || status=$?
 
 echo $status > "$status_actual"