How does pip call Python.

00_README.md

前提

$ pyenv versions
  system (2.7.16)
  2.7.0
* 3.7.0 (set by /path/to/.pyenv/version)

Python 2.7.16 が呼ばれることを期待

$ python -m pip install -U robotframework
$ robot --version
Robot Framework 3.1.2 (Python 2.7.16 on darwin)

$ robot main.robot
[ ERROR ] Error in file 'path/to/main.robot': Importing test library 'path/to/DebugKeywords.py' failed: SyntaxError: invalid syntax (DebugKeywords.py, line 16)

↓
Python 3.7.0 が呼ばれることを期待

$ python3 -m pip install -U robotframework
$ robot --version
Robot Framework 3.1.2 (Python 3.7.0 on darwin)

$ robot main.robot
[ ERROR ] hello

01_main.robot

# main.robot
*** Settings ***
Library         SeleniumLibrary
Library         path/to/DebugKeywords.py

*** Test Cases ***
Main
    # DebugKeywords 内の check 関数が呼ばれる
    Check

02_DebugKeywords.py

# DebugKeywords.py

from robot.api import logger
from SeleniumLibrary.base import keyword
from robot.libraries.BuiltIn import BuiltIn
from SeleniumLibrary.base import LibraryComponent

class KeywordClass(LibraryComponent):
    def __init__(self, ctx):
        LibraryComponent.__init__(self, ctx)

    @keyword
    def check(self):
        # f-string is only supported after v3.6.4
        message = "hello"
        logger.error(f"{message}")


class DebugKeywords(object):
    ROBOT_LISTENER_API_VERSION = 2

    def __init__(self):
        self.ROBOT_LIBRARY_LISTENER = self

    def start_suite(self, name, attributes):
        sl = BuiltIn().get_library_instance('SeleniumLibrary')
        sl.add_library_components([KeywordClass(sl)])
        BuiltIn().reload_library('SeleniumLibrary')
        self.added = True