Add `nvm_die_on_prefix`

nvm.sh

@@ -1250,6 +1250,44 @@ nvm_npm_global_modules() {
   echo "$INSTALLS //// $LINKS"
 }
 
+nvm_die_on_prefix() {
+  local NVM_DELETE_PREFIX
+  NVM_DELETE_PREFIX="$1"
+  case "$NVM_DELETE_PREFIX" in
+    0|1) ;;
+    *)
+      echo >&2 'First argument "delete the prefix" must be zero or one'
+      return 1
+    ;;
+  esac
+  local NVM_COMMAND
+  NVM_COMMAND="$2"
+  if [ -z "$NVM_COMMAND" ]; then
+    echo >&2 'Second argument "nvm command" must be nonempty'
+    return 2
+  fi
+
+  if ! nvm_has 'npm'; then
+    return
+  fi
+  local NVM_NPM_PREFIX
+  NVM_NPM_PREFIX="$(npm config get prefix)"
+  if ! (nvm_tree_contains_path "$NVM_DIR" "$NVM_NPM_PREFIX" >/dev/null 2>&1); then
+    if [ "_$NVM_DELETE_PREFIX" = "_1" ]; then
+      npm config delete prefix
+    else
+      nvm deactivate >/dev/null 2>&1
+      echo >&2 "nvm is not compatible with the npm config \"prefix\" option: currently set to \"$NVM_NPM_PREFIX\""
+      if nvm_has 'npm'; then
+        echo >&2 "Run \`npm config delete prefix\` or \`$NVM_COMMAND\` to unset it."
+      else
+        echo >&2 "Run \`$NVM_COMMAND\` to unset it."
+      fi
+      return 3
+    fi
+  fi
+}
+
 nvm() {
   if [ $# -lt 1 ]; then
     nvm help

test/fast/Unit tests/nvm_die_on_prefix

@@ -0,0 +1,60 @@
+#!/bin/sh
+
+cleanup () {
+  alias nvm_has='\nvm_has'
+  alias npm='\npm'
+  unset -f nvm_has npm
+}
+die () { echo $@ ; exit 1; }
+
+. ../../../nvm.sh
+
+OUTPUT="$(nvm_die_on_prefix 2>&1)"
+EXPECTED_OUTPUT="First argument \"delete the prefix\" must be zero or one"
+EXIT_CODE="$(nvm_die_on_prefix >/dev/null 2>&1; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_die_on_prefix' did not error with '$EXPECTED_OUTPUT'; got '$OUTPUT'"
+[ "_$EXIT_CODE" = "_1" ] || die "'nvm_die_on_prefix' did not exit with 1; got "$EXIT_CODE""
+
+OUTPUT="$(nvm_die_on_prefix 2 2>&1)"
+EXPECTED_OUTPUT="First argument \"delete the prefix\" must be zero or one"
+EXIT_CODE="$(nvm_die_on_prefix 2 >/dev/null 2>&1; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_die_on_prefix 2' did not error with '$EXPECTED_OUTPUT'; got '$OUTPUT'"
+[ "_$EXIT_CODE" = "_1" ] || die "'nvm_die_on_prefix' did not exit with 1; got "$EXIT_CODE""
+
+OUTPUT="$(nvm_die_on_prefix 0 2>&1)"
+EXPECTED_OUTPUT="Second argument \"nvm command\" must be nonempty"
+EXIT_CODE="$(nvm_die_on_prefix 0 >/dev/null 2>&1; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_die_on_prefix 0' did not error with '$EXPECTED_OUTPUT'; got '$OUTPUT'"
+[ "_$EXIT_CODE" = "_2" ] || die "'nvm_die_on_prefix 0' did not exit with 2; got '$EXIT_CODE'"
+
+nvm_has() { return 1; } # ie, npm is not installed
+OUTPUT="$(nvm_die_on_prefix 0 foo 2>&1)"
+[ -z "$OUTPUT" ] || die "nvm_die_on_prefix was not a noop when nvm_has returns 1, got '$OUTPUT'"
+
+nvm_has() { return 0; }
+
+npm() {
+  local args
+  args="$@"
+  if [ "_$args" = "_config get prefix" ]; then
+    echo "$(nvm_version_dir new)/good prefix"
+  fi
+}
+OUTPUT="$(nvm_die_on_prefix 0 foo 2>&1)"
+[ -z "$OUTPUT" ] || die "'nvm_die_on_prefix' was not a noop when prefix is good; got '$OUTPUT'"
+
+npm() {
+  local args
+  args="$@"
+  if [ "_$args" = "_config get prefix" ]; then
+    echo "./bad prefix"
+  fi
+}
+OUTPUT="$(nvm_die_on_prefix 0 foo 2>&1)"
+EXPECTED_OUTPUT="nvm is not compatible with the npm config \"prefix\" option: currently set to \"./bad prefix\"
+Run \`npm config delete prefix\` or \`foo\` to unset it."
+EXIT_CODE="$(nvm_die_on_prefix 0 foo >/dev/null 2>&1; echo $?)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_die_on_prefix 0 foo' did not error with '$EXPECTED_OUTPUT' with bad prefix set; got '$OUTPUT'"
+[ "_$EXIT_CODE" = "_3" ] || die "'nvm_die_on_prefix 0 foo' did not exit with 3 with bad prefix set; got '$EXIT_CODE'"
+
+cleanup