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core: Add @go.select_option function and demo
While starting to write my first "real" application/plugin, I realized that this function would eliminate a lot of repetitive boilerplate between scripts for the common single-option selection case.
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‎go-core.bash‎

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@@ -215,6 +215,43 @@ declare _GO_INJECT_MODULE_PATH="$_GO_INJECT_MODULE_PATH"
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return "$result"
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}
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# Prompts the user to select one item from a list of options.
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#
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# This is a thin wrapper around the `select` builtin command for
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# straightforward, single-option user prompts. If you need to do anything more
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# complex, use the `select` builtin command directly.
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#
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# This will prompt the user for a single input, returned in the caller-declared
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# variable identified by `result_var`. If the user enters an invalid option,
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# this will notify the user and prompt again. If the user terminates input (via
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# EOF, i.e. Ctrl-D), `result_var` will remain unchanged and the function will
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# return nonzero.
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#
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# Globals:
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# PS3 environment variable defining the selection prompt
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#
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# Arguments:
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# result_var: Name of the caller-declared variable used to store the option
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# ...: Strings representing options available for the user to select
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#
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# Returns:
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# zero if `result_var` contains the user's selection, nonzero otherwise
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@go.select_option() {
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local __go_selected_option
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select __go_selected_option in "${@:2}"; do
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case "$__go_selected_option" in
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'')
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@go.printf '"%s" is not a valid option.\n' "$REPLY" >&2
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;;
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*)
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printf -v "$1" -- '%s' "$__go_selected_option"
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break
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;;
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esac
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done
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[[ -n "$__go_selected_option" ]]
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}
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# Searches through plugin directories using a helper function
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#
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# The search will begin in `_GO_SCRIPTS_DIR/plugins`. As long as `search_func`

‎libexec/demo-core.d/select-option‎

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#! /usr/bin/env bash
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#
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# Demonstration of the `@go.select_option` function
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#
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# Usage:
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# [PS3=<VALUE>] {{go}} {{cmd}} [option...]
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#
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# Where:
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# PS3 environment variable defining the selection prompt
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# option... (Optional) list of user-selectable options, overriding defaults
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#
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# Use this program to get a feel for the core `@go.select_option` function, and
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# for an example of how to use it in your own scripts.
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select_option_demo() {
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local options=("$@")
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local selected
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local finish
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if [[ "${#options[@]}" -eq '0' ]]; then
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options=('Hello, World!' 'Goodbye, World!')
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fi
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while [[ -z "$finish" ]]; do
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@go.printf 'Please select one of the following options:\n'
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if @go.select_option 'selected' "${options[@]}"; then
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@go.printf 'You selected: "%s"\n\n' "$selected"
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else
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@go.printf 'You declined to select an option.\n\n'
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fi
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@go.printf 'Would you like to select another option?\n'
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if @go.select_option 'selected' 'Yes' 'No'; then
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if [[ "$selected" == 'No' ]]; then
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@go.printf 'Exiting...\n'
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finish='true'
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else
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printf '\n'
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fi
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else
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@go.printf 'You declined to select an option. Exiting...\n'
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finish='true'
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fi
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done
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}
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select_option_demo "$@"

‎tests/core/select-option.bats‎

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#! /usr/bin/env bats
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load ../environment
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setup() {
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test_filter
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@go.create_test_go_script 'declare selection' \
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'if @go.select_option "selection" "$@"; then' \
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' printf "\nSelection: \"%s\"\n" "$selection"' \
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'else' \
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' exit 1' \
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'fi'
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export PS3='Selection> '
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}
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teardown() {
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@go.remove_test_go_rootdir
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}
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@test "$SUITE: no options exits instantly" {
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run "$TEST_GO_SCRIPT"
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assert_failure ''
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}
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@test "$SUITE: single option selection" {
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run "$TEST_GO_SCRIPT" 'foo' <<<"1"
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assert_success '1) foo' \
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"$PS3" \
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'Selection: "foo"'
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}
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@test "$SUITE: multiple option selection" {
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run "$TEST_GO_SCRIPT" 'foo' 'bar' 'baz' <<<"2"
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assert_success '1) foo' \
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'2) bar' \
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'3) baz' \
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"$PS3" \
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'Selection: "bar"'
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}
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@test "$SUITE: select valid option after invalid option" {
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run "$TEST_GO_SCRIPT" 'foo' 'bar' 'baz' <<<$'0\n3'
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assert_success '1) foo' \
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'2) bar' \
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'3) baz' \
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"$PS3\"0\" is not a valid option." \
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"$PS3" \
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'Selection: "baz"'
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}
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@test "$SUITE: no selection with invalid option followed by end-of-file" {
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printf '4\n' >"$TEST_GO_ROOTDIR/input.txt"
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run "$TEST_GO_SCRIPT" 'foo' 'bar' 'baz' <"$TEST_GO_ROOTDIR/input.txt"
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assert_failure '1) foo' \
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'2) bar' \
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'3) baz' \
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"$PS3\"4\" is not a valid option." \
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"$PS3"
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}

‎tests/demo-core/select-option.bats‎

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#! /usr/bin/env bats
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load ../environment
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setup() {
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test_filter
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export PS3='Selection> '
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}
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teardown() {
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@go.remove_test_go_rootdir
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}
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@test "$SUITE: use default selection options" {
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run "$_GO_SCRIPT" demo-core select-option <<<$'1\n1\n2\n2\n'
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assert_success
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split_bats_output_into_lines
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assert_lines_equal 'Please select one of the following options:' \
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'1) Hello, World!' \
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'2) Goodbye, World!' \
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"${PS3}You selected: \"Hello, World!\"" \
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'' \
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'Would you like to select another option?' \
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'1) Yes' \
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'2) No' \
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"${PS3}" \
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'Please select one of the following options:' \
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'1) Hello, World!' \
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'2) Goodbye, World!' \
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"${PS3}You selected: \"Goodbye, World!\"" \
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'' \
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'Would you like to select another option?' \
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'1) Yes' \
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'2) No' \
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"${PS3}Exiting..."
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}
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@test "$SUITE: use user-provided selection options" {
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run "$_GO_SCRIPT" demo-core select-option foo bar baz <<<$'2\n2\n'
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assert_success
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split_bats_output_into_lines
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assert_lines_equal 'Please select one of the following options:' \
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'1) foo' \
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'2) bar' \
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'3) baz' \
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"${PS3}You selected: \"bar\"" \
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'' \
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'Would you like to select another option?' \
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'1) Yes' \
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'2) No' \
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"${PS3}Exiting..."
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}
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@test "$SUITE: exit both prompts on empty input" {
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mkdir "$TEST_GO_ROOTDIR"
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printf '' >"$TEST_GO_ROOTDIR/input.txt"
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run "$_GO_SCRIPT" demo-core select-option foo bar baz \
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<"$TEST_GO_ROOTDIR/input.txt"
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assert_success
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split_bats_output_into_lines
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assert_lines_equal 'Please select one of the following options:' \
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'1) foo' \
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'2) bar' \
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'3) baz' \
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"${PS3}" \
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'You declined to select an option.' \
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'' \
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'Would you like to select another option?' \
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'1) Yes' \
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'2) No' \
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"${PS3}" \
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'You declined to select an option. Exiting...'
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}

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