[Refactor] add `nvm_stdout_is_terminal` helper

nvm.sh

@@ -16,6 +16,10 @@ nvm_is_zsh() {
   [ -n "${ZSH_VERSION-}" ]
 }
 
+nvm_stdout_is_terminal() {
+  [ -t 1 ]
+}
+
 nvm_echo() {
   command printf %s\\n "$*" 2>/dev/null
 }
@@ -3499,7 +3503,7 @@ nvm() {
         nvm_print_default_alias nvm_print_formatted_alias nvm_resolve_local_alias \
         nvm_sanitize_path nvm_has_colors nvm_process_parameters \
         node_version_has_solaris_binary iojs_version_has_solaris_binary \
-        nvm_curl_libz_support nvm_command_info nvm_is_zsh \
+        nvm_curl_libz_support nvm_command_info nvm_is_zsh nvm_stdout_is_terminal \
         >/dev/null 2>&1
       unset NVM_RC_VERSION NVM_NODEJS_ORG_MIRROR NVM_IOJS_ORG_MIRROR NVM_DIR \
         NVM_CD_FLAGS NVM_BIN NVM_MAKE_JOBS \

test/fast/Unit tests/nvm_stdout_is_terminal

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+tempfile=$(mktemp)
+
+die () { echo "$@" ; cleanup; exit 1; }
+cleanup() { rm -f "$tempfile"; }
+
+\. ../../../nvm.sh
+
+if [ -t 1 ] ; then
+  # test is running in a terminal, e.g. locally
+  nvm_stdout_is_terminal || die 'nvm_stdout_is_terminal should be true'
+  nvm_stdout_is_terminal 2>/dev/null || die 'nvm_stdout_is_terminal should be true when stderr is redirected'
+  nvm_stdout_is_terminal </dev/null || die 'nvm_stdout_is_terminal should be true when stdin is redirected'
+else
+  # test is not running in a terminal, e.g. on travis-ci
+  ! nvm_stdout_is_terminal || die 'nvm_stdout_is_terminal should be false'
+  ! nvm_stdout_is_terminal 2>/dev/null || die 'nvm_stdout_is_terminal should be false when stderr is redirected'
+  ! nvm_stdout_is_terminal </dev/null || die 'nvm_stdout_is_terminal should be false when stdin is redirected'
+fi
+
+(! nvm_stdout_is_terminal || echo "boo!") | read && die 'nvm_stdout_is_terminal should be false when stdout goes to a pipe'
+! nvm_stdout_is_terminal >/dev/null || die 'nvm_stdout_is_terminal should be false when stdout goes to /dev/null'
+! nvm_stdout_is_terminal >"$tempfile" || die 'nvm_stdout_is_terminal should be false when stdout goes to a file'
+[ "$(nvm_stdout_is_terminal; echo $?)" = "1" ] || die 'nvm_stdout_is_terminal should be false in command substitution'
+
+# also test the 'true' case while running on travis-ci or similar environments
+nvm_stdout_is_terminal >/dev/tty || die 'nvm_stdout_is_terminal should be true when stdout goes to /dev/tty'
+nvm_stdout_is_terminal >/dev/tty 2>/dev/null || die 'nvm_stdout_is_terminal should be true when stdout goes to /dev/tty and stderr is redirected'
+nvm_stdout_is_terminal >/dev/tty </dev/null || die 'nvm_stdout_is_terminal should be true when stdout goes to /dev/tty and stdin is redirected'
+
+cleanup