user configurable pre-post command hooks

Suppose a `foo` plugin is installed and provides a `bar` executable.
The following hooks will be executed when set in `.asdfrc`:

```shell
post_asdf_install_foo = echo installed foo version ${1}
post_asdf_reshim_foo = echo reshimmed foo version ${1}

pre_foo_bar = echo about to execute command bar from foo with args: ${@}
post_foo_bar = echo just executed command bar from foo with args: ${@}
```

CHANGELOG.md

@@ -4,6 +4,17 @@
 
 Features
 
+* Configurable command hooks from `.asdfrc`
+  Suppose a `foo` plugin is installed and provides a `bar` executable,
+  The following hooks will be executed when set:
+
+    ```shell
+    post_asdf_install_foo = echo installed foo version ${1}
+    post_asdf_reshim_foo = echo reshimmed foo version ${1}
+    
+    pre_foo_bar = echo about to execute command bar from foo with args: ${@}
+    post_foo_bar = echo just executed command bar from foo with args: ${@}
+    ```
 * New shim version meta-data allows shims to not depend on a particular plugin
   nor on its relative executable path (#431)
   Upgrading requires shim re-generation and should happen automatically by `asdf-exec`:

bin/private/asdf-tool-exec

@@ -35,19 +35,29 @@ if [ -z "$selected_version" ]; then
 fi
 
 if [ ! -z "$selected_version" ]; then
-  plugin=$(cut -d ' ' -f 1 <<< "$selected_version");
+  plugin_name=$(cut -d ' ' -f 1 <<< "$selected_version");
   version=$(cut -d ' ' -f 2- <<< "$selected_version");
-  plugin_path=$(get_plugin_path "$plugin")
+  plugin_path=$(get_plugin_path "$plugin_name")
 
-  plugin_exec_env $plugin $version
+  plugin_exec_env $plugin_name $version
   executable_path=$(command -v "$shim_name")
 
   if [ -x "${plugin_path}/bin/exec-path" ]; then
-    install_path=$(find_install_path "$plugin" "$version")
+    install_path=$(find_install_path "$plugin_name" "$version")
     executable_path=$(get_custom_executable_path "${plugin_path}" "${install_path}" "${executable_path}")
   fi
 
-  exec "$executable_path" "${@:2}"
+  asdf_run_hook "pre_${plugin_name}_${shim_name}" "${@:2}"
+  pre_status=$?
+  if [ "$pre_status" -eq 0 ]; then
+    "$executable_path" "${@:2}"
+    exit_status=$?
+  fi
+  if [ "${exit_status:-${pre_status}}" -eq 0 ]; then
+    asdf_run_hook "post_${plugin_name}_${shim_name}" "${@:2}"
+    post_status=$?
+  fi
+  exit "${post_status:-${exit_status:-${pre_status}}}"
 fi
 
 (

lib/commands/install.sh

@@ -102,6 +102,7 @@ install_tool_version() {
     local exit_code=$?
     if [ $exit_code -eq 0 ]; then
       reshim_command "$plugin_name" "$full_version"
+      asdf_run_hook "post_asdf_install_${plugin_name}" "$full_version"
     else
       handle_failure "$install_path"
     fi

lib/commands/reshim.sh

@@ -21,6 +21,7 @@ reshim_command() {
   if [ "$full_version" != "" ]; then
     # generate for the whole package version
     generate_shims_for_version "$plugin_name" "$full_version"
+    asdf_run_hook "post_asdf_reshim_$plugin_name" "$full_version"
   else
     # generate for all versions of the package
     local plugin_installs_path
@@ -31,8 +32,10 @@ reshim_command() {
       full_version_name=$(basename "$install" | sed 's/ref\-/ref\:/')
       generate_shims_for_version "$plugin_name" "$full_version_name"
       remove_obsolete_shims "$plugin_name" "$full_version_name"
+      asdf_run_hook "post_asdf_reshim_$plugin_name" "$full_version_name"
     done
   fi
+
 }
 
 

lib/utils.sh

@@ -310,7 +310,7 @@ get_asdf_config_value_from_file() {
   fi
 
   local result
-  result=$(grep -E "^\\s*$key\\s*=" "$config_path" | awk -F '=' '{ gsub(/ /, "", $2); print $2 }')
+  result=$(grep -E "^\\s*$key\\s*=\\s*" "$config_path" | head | awk -F '=' '{print $2}' | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')
   if [ -n "$result" ]; then
     echo "$result"
   fi
@@ -540,3 +540,15 @@ shim_plugin_versions() {
 }
 
 
+asdf_run_hook() {
+  local hook_name=$1
+  local hook_cmd
+  hook_cmd="$(get_asdf_config_value "$hook_name")"
+  if [ -n "$hook_cmd" ]; then
+    asdf_hook_fun() {
+      unset asdf_hook_fun
+      ev'al' "$hook_cmd" # ignore banned command just here
+    }
+    asdf_hook_fun "${@:2}"
+  fi
+}

test/install_command.bats

@@ -138,3 +138,12 @@ teardown() {
   [ "$status" -eq 0 ]
   [ ! -f $ASDF_DIR/installs/dummy/system/version ]
 }
+
+@test "install command executes configured post plugin install hook" {
+  cat > $HOME/.asdfrc <<-'EOM'
+post_asdf_install_dummy = eval echo HEY $version FROM $plugin_name
+EOM
+
+  run install_command dummy 1.0
+  [ "$output" == "HEY 1.0 FROM dummy" ]
+}

test/reshim_command.bats

@@ -98,3 +98,14 @@ teardown() {
   [ "$status" -eq 0 ]
   [ "1" -eq "$(ls $ASDF_DIR/shims/dummy* | wc -l)" ]
 }
+
+@test "reshim command executes configured post hook" {
+  run install_command dummy 1.0
+
+  cat > $HOME/.asdfrc <<-'EOM'
+post_asdf_reshim_dummy = echo RESHIM
+EOM
+
+  run reshim_command dummy 1.0
+  [ "$output" == "RESHIM" ]
+}

test/shim_exec.bats

@@ -279,3 +279,65 @@ teardown() {
   run $ASDF_DIR/shims/dummy
   [ "$output" == "CUSTOM" ]
 }
+
+@test "shim exec executes configured pre-hook" {
+  run install_command dummy 1.0
+  echo dummy 1.0 > $PROJECT_DIR/.tool-versions
+
+  cat > $HOME/.asdfrc <<-'EOM'
+pre_dummy_dummy = echo PRE $version $1 $2
+EOM
+
+  run $ASDF_DIR/shims/dummy hello world
+  [ "$status" -eq 0 ]
+  echo "$output" | grep "PRE 1.0 hello world"
+  echo "$output" | grep "This is Dummy 1.0! world hello"
+}
+
+@test "shim exec doesnt execute command if pre-hook failed" {
+  run install_command dummy 1.0
+  echo dummy 1.0 > $PROJECT_DIR/.tool-versions
+
+  mkdir $HOME/hook
+  pre_cmd="$HOME/hook/pre"
+  echo 'echo $* && false' > "$pre_cmd"
+  chmod +x "$pre_cmd"
+
+  cat > $HOME/.asdfrc <<'EOM'
+pre_dummy_dummy = pre $1 no $plugin_name $2
+EOM
+
+  run env PATH=$PATH:$HOME/hook $ASDF_DIR/shims/dummy hello world
+  [ "$output" == "hello no dummy world" ]
+  [ "$status" -eq 1 ]
+}
+
+@test "shim exec executes configured post-hook if command was successful" {
+  run install_command dummy 1.0
+  echo dummy 1.0 > $PROJECT_DIR/.tool-versions
+
+  cat > $HOME/.asdfrc <<-'EOM'
+post_dummy_dummy = echo POST $version $1 $2
+EOM
+
+  run $ASDF_DIR/shims/dummy hello world
+  [ "$status" -eq 0 ]
+  echo "$output" | grep "This is Dummy 1.0! world hello"
+  echo "$output" | grep "POST 1.0 hello world"
+}
+
+@test "shim exec does not executes configured post-hook if command failed" {
+  run install_command dummy 1.0
+  echo dummy 1.0 > $PROJECT_DIR/.tool-versions
+
+  cat > $HOME/.asdfrc <<-'EOM'
+post_dummy_dummy = echo POST
+EOM
+
+  echo "false" > $ASDF_DIR/installs/dummy/1.0/bin/dummy
+  chmod +x $ASDF_DIR/installs/dummy/1.0/bin/dummy
+
+  run $ASDF_DIR/shims/dummy hello world
+  [ "$status" -eq 1 ]
+  [ "$output" == "" ]
+}