[Fix] Improve nvm_is_version_installed to check for a node executable instead of root dir

test/fast/Aliases/setup

@@ -1,11 +1,14 @@
 #!/bin/sh
 
+\. ../../../nvm.sh
+\. ../../common.sh
+
 for i in $(seq 1 10)
   do
   echo 0.0.$i > ../../../alias/test-stable-$i
-  mkdir -p ../../../v0.0.$i
+  make_fake_node v0.0.$i
   echo 0.1.$i > ../../../alias/test-unstable-$i
-  mkdir -p ../../../v0.1.$i
+  make_fake_node v0.1.$i
   echo 0.2.$i > ../../../alias/test-iojs-$i
-  mkdir -p ../../../versions/io.js/v0.2.$i
+  make_fake_iojs v0.2.$i
 done

test/fast/Running "nvm deactivate" should unset the nvm environment variables.

@@ -2,13 +2,14 @@
 
 set -ex
 
-mkdir -p ../../v0.2.3
-
 die () { echo "$@" ; exit 1; }
 
-[ `expr $PATH : ".*v0.2.3/.*/bin.*"` = 0 ] || echo "WARNING: Unexpectedly found v0.2.3 already active" >&2
-
 \. ../../nvm.sh
+\. ../common.sh
+
+make_fake_node v0.2.3
+
+[ `expr $PATH : ".*v0.2.3/.*/bin.*"` = 0 ] || echo "WARNING: Unexpectedly found v0.2.3 already active" >&2
 
 nvm use --delete-prefix v0.2.3 || die "Failed to activate v0.2.3"
 [ `expr "$PATH" : ".*v0.2.3/.*/bin.*"` != 0 ] || die "PATH not set up properly"

test/fast/Running "nvm uninstall" should remove the appropriate directory.

@@ -2,11 +2,11 @@
 
 set -ex
 
-cd ../..
-mkdir v0.0.1
-mkdir src/node-v0.0.1
+\. ../../nvm.sh
+\. ../common.sh
+
+make_fake_node v0.0.1
 
-. ./nvm.sh
 nvm uninstall v0.0.1
 
-[ ! -d 'v0.0.1' ] && [ ! -d 'src/node-v0.0.1/files' ]
+[ ! -d 'v0.0.1' ]

test/fast/Running "nvm uninstall" with incorrect file permissions fails nicely

@@ -2,13 +2,11 @@
 
 set -ex
 
-cd ../..
-mkdir v0.0.1
-mkdir src/node-v0.0.1
+\. ../../nvm.sh
+\. ../common.sh
 
-sudo touch v0.0.1/sudo
-
-. ./nvm.sh
+make_fake_node v0.0.1
+sudo touch ""$(nvm_version_path v0.0.1)"/sudo"
 
 RETURN_MESSAGE="$(nvm uninstall v0.0.1 2>&1 || echo)"
 CHECK_FOR="Cannot uninstall, incorrect permissions on installation folder"