How to put string on two lines in Python?

Question

I am brand new to the world of Python, PyCharm, and Web API testing.

I am trying to test error message that gets displayed when an error is made in Web API. This error message has two parts and are displayed on two separate lines.

But somehow any string definition I generate for comparison is always displayed on one line.

This is one of the things I tried - created a string with new line \n between two parts.

    wp_error = 'This page can\'t be saved.\n Some required information is missing.'

    # create new workspace and save it without filling up any information.
    self.test_mycode.click_and_wait(self.workspace_overview.new_workspace_button,
                                     self.new_workspace._save_button_locator)
    self.new_workspace.save_button.click()

    self.message.check_message('error', wp_error)

But this didn't work and I got:

in check_message Assert.equal(message.message_body.text, message_text)

self = <class 'unittestzero.Assert'>
first = "This page can't be saved.
Some required information is missing."
second = "This page can't be saved.\n Some required information is missing."
.....

>       assert first == second, msg
E       AssertionError: None

So my question is how do I define the string to appropriately test the error message that appears on two lines? Thank you.

@user2864740, what is wrong in the OP's `wp_error` line? – Padraic Cunningham Oct 24 '14 at 20:44 — Padraic Cunningham, Oct 24 '14 at 20:44
@PadraicCunningham Good call, I misread the symptoms. – user2864740 Oct 24 '14 at 20:51 — user2864740, Oct 24 '14 at 20:51

Jonathan Eunice · Answer 1 · 2014-10-24T21:36:09.850

If:

first = """This page can't be saved.
Some required information is missing."""
second = "This page can't be saved.\n Some required information is missing."
assert first == second

fails, then the problem is probably that:

first  == "This page can't be saved.\nSome required information is missing."
second == "This page can't be saved.\n Some required information is missing."

I.e. there is an extra space in the second one, after the newline. (Note also the triple quotes, to allow a string to span lines without the compiler complaining,)

Solutions: You can either:

Be extremely careful with your test data.
Use a "shim" to allow "approximately equals". For example:
```
import re
FOLD_WHITESPACE = re.compile(r'\s+')

def oneline(s):
   return FOLD_WHITESPACE.sub(" ", s)

assert oneline(first) == oneline(second)
```
I am not arguing that this particular transformation is the ideal one for all string comparisons, but it's a simple one that gets at your need to not be excessively concerned with whitespaces (including line breaks).

Similar "almost equals" or "transformed equals" tests are often convenient or required for testing both string and floating point values.

Btw, if you're using the object call version of assert, it might be couched as:
```
Assert.equal(oneline(message.message_body.text),
             oneline(message_text))
```

I was thinking the same thing, but I'm confused as to why the test runner would seem to *print* `first` (or at least interpret the newlines), and on the other hand display the `repr()` of `second`? — Lukas Graf, Oct 24 '14 at 21:19
@LukasGraf Good point. I don't entirely trust the code as presented. I mean, how do you get `self = ` either? As an equals `==` okay, but as an assignment? That's not legit Python. But, my test runner output (pytest and fox) looks very different. So I overlooked those quirks. — Jonathan Eunice, Oct 24 '14 at 21:30

How to put string on two lines in Python?

1 Answers1