[Tests] Add unit test for nvm_download

test/fast/Unit tests/nvm_download

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+cleanup () {
+  unset -f die cleanup
+}
+die () { echo "$@" ; cleanup ; exit 1; }
+
+\. ../../../nvm.sh
+
+set -ex
+
+# nvm_download install.sh
+nvm_download "https://raw.githubusercontent.com/nvm-sh/nvm/master/install.sh" >/dev/null || die "nvm_download unable to download install.sh"
+
+# nvm_download should fail to download wrong_install.sh
+! nvm_download "https://raw.githubusercontent.com/nvm-sh/nvm/master/wrong_install.sh" >/dev/null || die "nvm_download should fail to download no existing file"
+
+cleanup

test/install_script/nvm_download

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+cleanup () {
+  unset -f die cleanup
+}
+die () { echo "$@" ; cleanup ; exit 1; }
+
+NVM_ENV=testing \. ../../install.sh
+
+# nvm_download install.sh
+nvm_download "https://raw.githubusercontent.com/nvm-sh/nvm/master/install.sh" >/dev/null || die "nvm_download unable to download install.sh"
+
+# nvm_download should fail to download wrong_install.sh
+if nvm_download "https://raw.githubusercontent.com/nvm-sh/nvm/master/wrong_install.sh" &>/dev/null; then
+  die "nvm_download should fail to download no existing file"
+fi
+
+cleanup