Add error checking to nvm_tree_contains_path

nvm.sh

@@ -58,6 +58,12 @@ nvm_tree_contains_path() {
   tree="$1"
   local node_path
   node_path="$2"
+
+  if [ "@$tree@" = "@@" ] || [ "@$node_path@" = "@@" ]; then
+    >&2 echo "both the tree and the node path are required"
+    return 2
+  fi
+
   local pathdir
   pathdir=$(dirname "$node_path")
   while [ "$pathdir" != "" ] && [ "$pathdir" != "." ] && [ "$pathdir" != "/" ] && [ "$pathdir" != "$tree" ]; do

test/fast/Unit tests/nvm_tree_contains_path

@@ -15,6 +15,11 @@ touch tmp/node
 mkdir -p tmp2
 touch tmp2/node
 
+[ "$(nvm_tree_contains_path 2>&1)" = "both the tree and the node path are required" ] || die 'incorrect error message with no args'
+[ "$(nvm_tree_contains_path > /dev/null 2>&1 ; echo $?)" = "2" ] || die 'incorrect error code with no args'
+[ "$(nvm_tree_contains_path tmp 2>&1)" = "both the tree and the node path are required" ] || die 'incorrect error message with one arg'
+[ "$(nvm_tree_contains_path > /dev/null 2>&1 ; echo $?)" = "2" ] || die 'incorrect error code with one arg'
+
 nvm_tree_contains_path tmp tmp/node || die '"tmp" should contain "tmp/node"'
 
 nvm_tree_contains_path tmp tmp2/node && die '"tmp" should not contain "tmp2/node"'