Add "shell" subcommand for setting versions in shell session

Add a "shell" command similar to the existing "global" and "local"
commands, which sets the version in an environment variable instead of
writing it to a file. This was inspired by the similar functionality in
rbenv.

It works by adding a wrapper function for the asdf command. It forwards
to a "sh-shell" command that returns the exports as shell code which is
then evaled by the wrapper. This is a little gross, but we need to run
the code in the shell context in order to set variables.

Resolves #378

asdf.fish

@@ -13,3 +13,18 @@ for x in $asdf_bin_dirs
     set -gx fish_user_paths $fish_user_paths $x
   end
 end
+
+# Add function wrapper so we can export variables
+function asdf
+  set command $argv[1]
+  set -e argv[1]
+
+  switch "$command"
+  case "shell"
+    # eval commands that need to export variables
+    source (env ASDF_SHELL=fish asdf "sh-$command" $argv | psub)
+  case '*'
+    # forward other commands to asdf script
+    command asdf "$command" $argv
+  end
+end

asdf.sh

@@ -23,6 +23,25 @@ ASDF_USER_SHIMS="${ASDF_DATA_DIR:-$HOME/.asdf}/shims"
 PATH="${ASDF_BIN}:$PATH"
 PATH="${ASDF_USER_SHIMS}:$PATH"
 
+# Add function wrapper so we can export variables
+asdf() {
+  local command
+  command="$1"
+  if [ "$#" -gt 0 ]; then
+    shift
+  fi
+
+  case "$command" in
+    "shell")
+      # eval commands that need to export variables
+      eval "$(asdf "sh-$command" "$@")";;
+    *)
+      # forward other commands to asdf script
+      command asdf "$command" "$@";;
+
+  esac
+}
+
 if [ -n "$ZSH_VERSION" ]; then
   autoload -U bashcompinit
   bashcompinit

bin/asdf

@@ -46,6 +46,14 @@ case "$1" in
     load_cmd "current" "plugin-list"
     current_command "${cmd_args[@]}";;
 
+  "sh-shell")
+    load_cmd "version_commands"
+    shell_command "${cmd_args[@]}";;
+
+  "shell")
+    echo "Shell integration is not enabled. Please ensure you source asdf in your shell setup."
+    exit 1;;
+
   "local")
     load_cmd "version_commands"
     local_command "${cmd_args[@]}";;

completions/asdf.bash

@@ -46,7 +46,7 @@ _asdf () {
       # shellcheck disable=SC2207
       COMPREPLY=($(compgen -W "--head" -- "$cur"))
       ;;
-    uninstall|where|reshim|local|global)
+    uninstall|where|reshim|local|global|shell)
       if [[ "$plugins" == *"$prev"* ]] ; then
         local versions
         versions=$(asdf list "$prev" 2> /dev/null)
@@ -58,7 +58,7 @@ _asdf () {
       fi
       ;;
     *)
-      local cmds='current global help install list list-all local plugin-add plugin-list plugin-list-all plugin-remove plugin-update reshim uninstall update where which '
+      local cmds='current global help install list list-all local plugin-add plugin-list plugin-list-all plugin-remove plugin-update reshim shell uninstall update where which '
       # shellcheck disable=SC2207
       COMPREPLY=($(compgen -W "$cmds" -- "$cur"))
       ;;

completions/asdf.fish

@@ -105,6 +105,11 @@ complete -f -c asdf -n '__fish_asdf_needs_command' -a global -d "Set global vers
 complete -f -c asdf -n '__fish_asdf_using_command global; and __fish_asdf_arg_number 2' -a '(__fish_asdf_plugin_list)'
 complete -f -c asdf -n '__fish_asdf_using_command global; and test (count (commandline -opc)) -gt 2' -a '(__fish_asdf_list_versions (__fish_asdf_arg_at 3)) system'
 
+# shell completion
+complete -f -c asdf -n '__fish_asdf_needs_command' -a shell -d "Set version for a plugin in current shell session"
+complete -f -c asdf -n '__fish_asdf_using_command shell; and __fish_asdf_arg_number 2' -a '(__fish_asdf_plugin_list)'
+complete -f -c asdf -n '__fish_asdf_using_command shell; and test (count (commandline -opc)) -gt 2' -a '(__fish_asdf_list_versions (__fish_asdf_arg_at 3)) system'
+
 # misc
 complete -f -c asdf -n '__fish_asdf_needs_command' -l "help" -d "Displays help"
 complete -f -c asdf -n '__fish_asdf_needs_command' -l "version" -d "Displays asdf version"

lib/commands/version_commands.sh

@@ -77,3 +77,31 @@ global_command() {
   # shellcheck disable=2068
   version_command "global" $@
 }
+
+# Output from this command must be executable shell code
+shell_command() {
+  if [ "$#" -lt "2" ]; then
+    echo "Usage: asdf shell <name> <version>" >&2
+    echo 'false'
+    exit 1
+  fi
+
+  local plugin=$1
+  local version=$2
+
+  if ! (check_if_version_exists "$plugin" "$version"); then
+    echo 'false'
+    exit 1
+  fi
+
+  local upcase_name
+  upcase_name=$(echo "$plugin" | tr '[:lower:]-' '[:upper:]_')
+  local version_env_var="ASDF_${upcase_name}_VERSION"
+
+  case $ASDF_SHELL in
+    fish )
+      echo "set -gx $version_env_var \"$version\"";;
+    * )
+      echo "export $version_env_var=\"$version\"";;
+  esac
+}

test/version_commands.bats

@@ -230,3 +230,48 @@ teardown() {
   [ -L $HOME/.tool-versions ]
   [ "$(cat other-dir/.tool-versions)" = "dummy 1.1.0" ]
 }
+
+@test "shell wrapper function should export ENV var" {
+  source $(dirname "$BATS_TEST_DIRNAME")/asdf.sh
+  asdf shell "dummy" "1.1.0"
+  [ $(echo $ASDF_DUMMY_VERSION) = "1.1.0" ]
+  unset ASDF_DUMMY_VERSION
+}
+
+@test "shell wrapper function should return an error for missing plugins" {
+  source $(dirname "$BATS_TEST_DIRNAME")/asdf.sh
+  run asdf shell "nonexistent" "1.0.0"
+  [ "$status" -eq 1 ]
+  [ "$output" = "No such plugin: nonexistent" ]
+}
+
+@test "shell should emit an error when wrapper function is not loaded" {
+  run asdf shell "dummy" "1.1.0"
+  echo $output
+  [ "$status" -eq 1 ]
+  [ "$output" = "Shell integration is not enabled. Please ensure you source asdf in your shell setup." ]
+}
+
+@test "sh-shell should emit an error when plugin does not exist" {
+  run asdf sh-shell "nonexistent" "1.0.0"
+  [ "$status" -eq 1 ]
+  [ "$output" = $'No such plugin: nonexistent\nfalse' ]
+}
+
+@test "sh-shell should emit an error when version does not exist" {
+  run asdf sh-shell "dummy" "nonexistent"
+  [ "$status" -eq 1 ]
+  [ "$output" = $'version nonexistent is not installed for dummy\nfalse' ]
+}
+
+@test "sh-shell should export version if it exists" {
+  run asdf sh-shell "dummy" "1.1.0"
+  [ "$status" -eq 0 ]
+  [ "$output" = "export ASDF_DUMMY_VERSION=\"1.1.0\"" ]
+}
+
+@test "sh-shell should use set when shell is fish" {
+  ASDF_SHELL=fish run asdf sh-shell "dummy" "1.1.0"
+  [ "$status" -eq 0 ]
+  [ "$output" = "set -gx ASDF_DUMMY_VERSION \"1.1.0\"" ]
+}