[test] Add unit tests for nvm_is_version_installed

test/fast/Unit tests/nvm_is_version_installed

@@ -0,0 +1,38 @@
+#!/bin/sh
+
+cleanup () {
+  rm -rf "$NVM_DIR"
+  unset -f die cleanup
+  unset NVM_DIR NODE_PATH
+}
+die () { echo "$@" ; cleanup ; exit 1; }
+
+\. ../../../nvm.sh
+
+set -ex
+
+NVM_DIR=$(mktemp -d)
+NODE_PATH="$NVM_DIR/versions/node"
+mkdir -p "$NODE_PATH"
+if [ -z "$NODE_PATH" ]; then
+  die 'Unable to create temporary folder'
+fi
+
+# nvm_is_version_installed is available
+type nvm_is_version_installed > /dev/null 2>&1 || die 'nvm_is_version_installed is not available'
+
+# nvm_is_version_installed with no parameter fails
+! nvm_is_version_installed || die 'nvm_is_version_installed without parameter should fail'
+
+# nvm_is_version_installed fails with non existing version
+! nvm_is_version_installed 12.0.0 || die 'nvm_is_version_installed 12.0.0 should fail with non existing version'
+
+# nvm_is_version_installed fails with non executable existing version
+mkdir -p "$NODE_PATH/12.0.0/bin" && cd "$NODE_PATH/12.0.0/bin" && touch "$NODE_PATH/12.0.0/bin/node"
+! nvm_is_version_installed 12.0.0 || die 'nvm_is_version_installed 12.0.0 should fail with non executable existing version'
+
+# nvm_is_version_installed whould work
+chmod +x "$NODE_PATH/12.0.0/bin/node"
+nvm_is_version_installed 12.0.0 || die 'nvm_is_version_installed 12.0.0 should work'
+
+cleanup