Add opt-in automatic Go version detection on directory change

ENVIRONMENT_VARIABLES.md

@@ -19,3 +19,4 @@ name | default | description
 `GOENV_AUTO_INSTALL_FLAGS` | | (Note: only works if `GOENV_AUTO_INSTALL` is set to 1) Appends flags to the auto install command (see `goenv install --help` for all available flags)
 `GOENV_RC_FILE` | `$HOME/.goenvrc` | If `GOENV_RC_FILE` is set, it will be modified accordingly.
 `GOENV_PATH_ORDER` | | If `GOENV_PATH_ORDER` is set to `front`, `$GOENV_ROOT/shims` will be prepended to the existing `PATH`.Set `GOENV_PATH_ORDER` to a configuration file named by `GOENV_RC_FILE`(e.g. `~/.goenvrc`), for example `GOENV_PATH_ORDER=front` in `~/.goenvrc`.
+`GOENV_AUTOMATICALLY_DETECT_VERSION` | `0` | If set to `1`, goenv will automatically update `GOROOT` and `GOPATH` when you change directories. This enables automatic version switching based on local `.go-version` files without needing to reload your shell configuration. **Note:** This feature adds a hook that runs on every directory change, which may have a slight performance impact.

INSTALL.md

@@ -62,6 +62,22 @@ export GOENV_ROOT="$HOME/.goenv"
 export PATH="$GOENV_ROOT/bin:$PATH"
 eval "$(goenv init -)"
 ```
+
+7. **(Optional) Enable automatic version detection on directory change.**
+   By default, when you `cd` into a directory with a `.go-version` file, the shims will use the correct Go version,
+   but environment variables like `GOROOT` and `GOPATH` won't update until you reload your shell.
+
+   To enable automatic updating of `GOROOT` and `GOPATH` when changing directories, set the following environment variable:
+
+   ```shell
+   export GOENV_AUTOMATICALLY_DETECT_VERSION=1
+   ```
+
+   Add this line **before** the `eval "$(goenv init -)"` line in your shell configuration file.
+
+   **Note:** This feature adds a hook that runs on every directory change (or before each prompt in bash/ksh),
+   which may have a slight performance impact. If you don't need `GOROOT` and `GOPATH` to update automatically,
+   you can leave this disabled and rely on the shims, which always work correctly.
 
 ## via ZPlug plugin manager for Zsh
 

libexec/goenv-init

@@ -189,3 +189,47 @@ if [ -z "$no_rehash" ]; then
   goenv rehash --only-manage-paths
 EOS
 fi
+
+# Add automatic version detection on directory change (opt-in via GOENV_AUTOMATICALLY_DETECT_VERSION)
+if [ -n "${GOENV_AUTOMATICALLY_DETECT_VERSION}" ] && [ "${GOENV_AUTOMATICALLY_DETECT_VERSION}" != "0" ]; then
+  case "$shell" in
+  fish)
+    cat <<'EOS'
+function __goenv_auto_detect_version --on-variable PWD
+  if test -n "$GOENV_AUTOMATICALLY_DETECT_VERSION"; and test "$GOENV_AUTOMATICALLY_DETECT_VERSION" != "0"
+    goenv rehash --only-manage-paths > /dev/null 2>&1
+  end
+end
+EOS
+    ;;
+  zsh)
+    cat <<'EOS'
+__goenv_auto_detect_version() {
+  if [ -n "${GOENV_AUTOMATICALLY_DETECT_VERSION}" ] && [ "${GOENV_AUTOMATICALLY_DETECT_VERSION}" != "0" ]; then
+    eval "$(goenv rehash --only-manage-paths)"
+  fi
+}
+if [[ ! "${chpwd_functions[*]}" =~ "__goenv_auto_detect_version" ]]; then
+  chpwd_functions+=(__goenv_auto_detect_version)
+fi
+EOS
+    ;;
+  *)
+    # bash, ksh, and other POSIX shells use PROMPT_COMMAND
+    cat <<'EOS'
+__goenv_auto_detect_version() {
+  if [ -n "${GOENV_AUTOMATICALLY_DETECT_VERSION}" ] && [ "${GOENV_AUTOMATICALLY_DETECT_VERSION}" != "0" ]; then
+    eval "$(goenv rehash --only-manage-paths)"
+  fi
+}
+if [[ ! "${PROMPT_COMMAND}" =~ "__goenv_auto_detect_version" ]]; then
+  if [ -n "${PROMPT_COMMAND}" ]; then
+    PROMPT_COMMAND="${PROMPT_COMMAND};__goenv_auto_detect_version"
+  else
+    PROMPT_COMMAND="__goenv_auto_detect_version"
+  fi
+fi
+EOS
+    ;;
+  esac
+fi

test/goenv-init.bats

@@ -311,3 +311,69 @@ OUT
 
   assert_success
 }
+
+@test "does not include automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is not set for bash" {
+  run goenv-init - bash
+
+  assert_success
+  assert [ -z "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+}
+
+@test "does not include automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is 0 for bash" {
+  GOENV_AUTOMATICALLY_DETECT_VERSION=0 run goenv-init - bash
+
+  assert_success
+  assert [ -z "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+}
+
+@test "includes automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is 1 for bash" {
+  GOENV_AUTOMATICALLY_DETECT_VERSION=1 run goenv-init - bash
+
+  assert_success
+  assert [ -n "$(echo "$output" | grep "__goenv_auto_detect_version()")" ]
+  assert [ -n "$(echo "$output" | grep "PROMPT_COMMAND=")" ]
+}
+
+@test "does not include automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is not set for zsh" {
+  run goenv-init - zsh
+
+  assert_success
+  assert [ -z "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+}
+
+@test "does not include automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is 0 for zsh" {
+  GOENV_AUTOMATICALLY_DETECT_VERSION=0 run goenv-init - zsh
+
+  assert_success
+  assert [ -z "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+}
+
+@test "includes automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is 1 for zsh" {
+  GOENV_AUTOMATICALLY_DETECT_VERSION=1 run goenv-init - zsh
+
+  assert_success
+  assert [ -n "$(echo "$output" | grep "__goenv_auto_detect_version()")" ]
+  assert [ -n "$(echo "$output" | grep "chpwd_functions")" ]
+}
+
+@test "does not include automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is not set for fish" {
+  run goenv-init - fish
+
+  assert_success
+  assert [ -z "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+}
+
+@test "does not include automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is 0 for fish" {
+  GOENV_AUTOMATICALLY_DETECT_VERSION=0 run goenv-init - fish
+
+  assert_success
+  assert [ -z "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+}
+
+@test "includes automatic version detection hook when GOENV_AUTOMATICALLY_DETECT_VERSION is 1 for fish" {
+  GOENV_AUTOMATICALLY_DETECT_VERSION=1 run goenv-init - fish
+
+  assert_success
+  assert [ -n "$(echo "$output" | grep "__goenv_auto_detect_version")" ]
+  assert [ -n "$(echo "$output" | grep "on-variable PWD")" ]
+}