prompt: Add read_prompt_response, prompt_for_input

Author: mbland

lib/prompt

@@ -3,10 +3,60 @@
 # User input prompts
 #
 # Exports:
+#   @go.read_prompt_response
+#     Reads a line, trims leading/trailing space, and sets a default if empty
+#
+#   @go.prompt_for_input
+#     Prompts the user for a line of input
+#
 #   @go.select_option
 #     Prompts the user to select one item from a list of options
 
-. "$_GO_USE_MODULES" 'validation'
+. "$_GO_USE_MODULES" 'strings' 'validation'
+
+# Reads a line, trims leading/trailing space, and sets a default if empty
+#
+# Arguments:
+#   var_name:  Name of the caller's variable into which to read value
+#   default:   (Optional) Default value if the input line is empty
+@go.read_prompt_response() {
+  @go.validate_identifier_or_die 'Input prompt response variable name' "$1"
+  read -r "$1"
+  @go.trim "$1"
+  printf -v "$1" -- '%s' "${!1:-$2}"
+}
+
+# Prompts the user for a line of input
+#
+# If the prompt doesn't end with a whitespace character, a space will be added
+# between the prompt and the input cursor. Otherwise the existing character will
+# be preserved.
+#
+# If a default value is specified, a space will be added to the prompt, followed
+# by the default value in square brackets; the caller should not add the default
+# value to the prompt directly. If the prompt ends with a whitespace character,
+# it will be preserved and added after the default value.
+#
+# Arguments:
+#   result_var  Name of the caller-declared variable for the result
+#   prompt      Text prompt for user input
+#   default     (Optional) Default value if response is empty
+#   fail_msg    (Optional) Failure message if empty input isn't valid
+@go.prompt_for_input() {
+  @go.validate_identifier_or_die 'Input prompt response variable name' "$1"
+
+  if [[ "$2" =~ [[:space:]]$ ]]; then
+    @go.printf '%s%s%s' "${2%?}" "${3:+ [default: $3]}" "${BASH_REMATCH[0]}" >&2
+  else
+    @go.printf '%s %s' "$2" "${3:+[default: $3] }" >&2
+  fi
+  @go.read_prompt_response "$1" "$3"
+
+  if [[ -z "${!1}" && -n "$4" ]]; then
+    @go.printf '%s\n' "$4" >&2
+    return 1
+  fi
+}
 
 # Prompts the user to select one item from a list of options.
 #

tests/prompt/prompt-for-input.bats

@@ -0,0 +1,64 @@
+#! /usr/bin/env bats
+
+load ../environment
+
+setup() {
+  test_filter
+  @go.create_test_go_script '. "$_GO_USE_MODULES" "prompt"' \
+    'declare prompt="$1"' \
+    'declare default="$2"' \
+    'declare fail_msg="$3"' \
+    'declare response="initial value"' \
+    'declare result' \
+    '@go.prompt_for_input "response" "$prompt" "$default" "$fail_msg"' \
+    'result="$?"' \
+    'printf -- "%s\n" "$response"' \
+    'exit "$result"'
+}
+
+teardown() {
+  @go.remove_test_go_rootdir
+}
+
+@test "$SUITE: error if variable not a valid identifier" {
+  @go.create_test_go_script '. "$_GO_USE_MODULES" "prompt"' \
+    '@go.prompt_for_input "invalid;"'
+
+  run "$TEST_GO_SCRIPT"
+  assert_failure
+
+  local err_msg='Input prompt response variable name "invalid;" for '
+  err_msg+='@go.prompt_for_input contains invalid identifier characters at:'
+
+  assert_lines_match "^${err_msg}\$" \
+    "^  $TEST_GO_SCRIPT:[0-9] main$"
+}
+
+@test "$SUITE: reads and trims value" {
+  run "$TEST_GO_SCRIPT" $'What is your quest?\n' <<<'  To seek the grail!   '
+  assert_success 'What is your quest?' \
+    'To seek the grail!'
+}
+
+@test "$SUITE: with default preserves prompt space" {
+  run "$TEST_GO_SCRIPT" $'What is your quest?\n' 'To seek the grail!' <<<''
+  assert_success 'What is your quest? [default: To seek the grail!]' \
+    'To seek the grail!'
+}
+
+@test "$SUITE: with default adds prompt space if missing" {
+  run "$TEST_GO_SCRIPT" 'What is your quest?' 'To seek the grail!' <<<''
+  assert_success \
+    'What is your quest? [default: To seek the grail!] To seek the grail!'
+}
+
+@test "$SUITE: reads empty input if no error message" {
+  run "$TEST_GO_SCRIPT" $'What is your quest?\n' <<<''
+  assert_success 'What is your quest?'
+}
+
+@test "$SUITE: fails with error message on empty input" {
+  run "$TEST_GO_SCRIPT" $'What is your quest?\n' '' 'Auuuuuuuugh!' <<<''
+  assert_failure 'What is your quest?' \
+    'Auuuuuuuugh!'
+}

tests/prompt/read-prompt-response.bats

@@ -0,0 +1,35 @@
+#! /usr/bin/env bats
+
+load ../environment
+
+setup() {
+  test_filter
+}
+
+teardown() {
+  @go.remove_test_go_rootdir
+}
+
+@test "$SUITE: error if response variable not a valid identifier" {
+  @go.create_test_go_script '. "$_GO_USE_MODULES" "prompt"' \
+    '@go.read_prompt_response "invalid;"'
+
+  run "$TEST_GO_SCRIPT"
+  assert_failure
+
+  local err_msg='Input prompt response variable name "invalid;" for '
+  err_msg+='@go.read_prompt_response contains invalid identifier characters at:'
+
+  assert_lines_match "^${err_msg}\$" \
+    "^  $TEST_GO_SCRIPT:[0-9] main$"
+}
+
+@test "$SUITE: reads and trims variable value, backslashes aren't special" {
+  @go.create_test_go_script '. "$_GO_USE_MODULES" "prompt"' \
+    'declare response="initial value"' \
+    '@go.read_prompt_response "response"' \
+    'printf -- "%s\n" "$response"'
+
+  run "$TEST_GO_SCRIPT" <<<"   Hello, World! \ Goodbye, World!  "
+  assert_success 'Hello, World! \ Goodbye, World!'
+}