Create `nvm_ensure_version_installed`

nvm.sh

@@ -189,6 +189,24 @@ nvm_version_path() {
   fi
 }
 
+nvm_ensure_version_installed() {
+  local PROVIDED_VERSION
+  PROVIDED_VERSION="$1"
+  local LOCAL_VERSION
+  LOCAL_VERSION="$(nvm_version "$PROVIDED_VERSION")"
+  local NVM_VERSION_DIR
+  NVM_VERSION_DIR="$(nvm_version_path "$LOCAL_VERSION")"
+  if [ ! -d "$NVM_VERSION_DIR" ]; then
+    VERSION="$(nvm_resolve_alias "$PROVIDED_VERSION")"
+    if [ $? -eq 0 ]; then
+      echo "N/A: version \"$PROVIDED_VERSION -> $VERSION\" is not yet installed" >&2
+    else
+      echo "N/A: version \"$(nvm_ensure_version_prefix "$PROVIDED_VERSION")\" is not yet installed" >&2
+    fi
+    return 1
+  fi
+}
+
 # Expand a version using the version cache
 nvm_version() {
   local PATTERN

test/fast/Unit tests/nvm_ensure_version_installed

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+die () { echo $@ ; cleanup ; exit 1; }
+cleanup () {
+  rm -rf "$(nvm_version_path v0.1.2)"
+}
+
+. ../../../nvm.sh
+
+mkdir -p "$(nvm_version_path v0.1.2)"
+
+OUTPUT="$(nvm_ensure_version_installed foo 2>&1)"
+EXIT_CODE=$?
+EXPECTED_OUTPUT='N/A: version "foo" is not yet installed'
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "expected 'nvm_ensure_version_installed foo' to give $EXPECTED_OUTPUT, got $OUTPUT"
+[ "_$EXIT_CODE" = "_1" ] || die "expected 'nvm_ensure_version_installed foo' to exit with 1, got $EXIT_CODE"
+
+OUTPUT="$(nvm_ensure_version_installed 0.1)"
+EXIT_CODE=$?
+[ "_$OUTPUT" = "_" ] || die "expected 'nvm_ensure_version_installed 0.1' to have no output, got $OUTPUT"
+[ "_$EXIT_CODE" = "_0" ] || die "expected 'nvm_ensure_version_installed 0.1' to exit with 0, got $EXIT_CODE"
+
+cleanup