Assertions

Assertions in Python

CSTesting for Python (C:\CSTesting-Python) exposes from cstesting import expect (cstesting/assertions.py). There is no browser.assertThat()—combine await on the browser/locator with expect(...) on plain values.

`expect(actual)` matchers

Matcher	Description
`to_be(expected)`	Identity (`is`)
`to_equal(expected)`	Deep / JSON-stable equality
`to_be_truthy()` / `to_be_falsy()`	Boolean coercion
`to_be_null()` / `to_be_defined()` / `to_be_undefined()`	None checks (undefined maps to None)
`to_throw(message?)`	`expect(fn).to_throw()` — sync or async callable
`to_be_greater_than(n)` / `to_be_less_than(n)`	Numeric
`to_contain(item)`	Substring or list membership
`to_have_length(n)`	Length
`expect(x).not_.to_be(y)`	Negation (use `not_` — `not` is reserved)

Page and element state

Use BrowserApi / LocatorApi async queries, then assert:

from cstesting import expect

visible = await browser.is_visible("h1")
expect(visible).to_be_truthy()

editable = await browser.locator("#email").is_editable()
expect(editable).to_be_truthy()

text = await browser.locator("h1").first().text_content()
expect(text).to_contain("Example")

title = await browser.evaluate("document.title")
expect(title).to_contain("Domain")

current = await browser.url()
expect("example.com" in current).to_be_truthy()

attr = await browser.locator("a").first().get_attribute("href")
expect(attr).to_be_defined()

API responses

For HTTP tests, assert on the chained response or on get_response() (see example/apitesting_test.py):

from cstesting import describe, it, expect, request

def _suite():
    it("status", lambda: (
        request.get("https://api.example.com/health")
        .expect_status(200)
    ))
    def raw():
        res = request.get("https://api.example.com/users/1")
        res.expect_status(200)
        r = res.get_response()
        expect(r.status).to_be(200)
    it("raw body", raw)

describe("API", _suite)

Playwright-style `expect(locator)`

Python CSTesting does not re-export Playwright’s auto-retrying expect. Use Playwright’s action timeouts and await browser.wait_for_selector(...) before reading state, then plain expect(...).

Usage

from cstesting import describe, it, expect

def _suite():
    it("math", lambda: expect(1 + 1).to_be(2))
    it("list", lambda: expect([1, 2]).to_contain(2))

describe("Unit", _suite)

Failures raise cstesting.AssertionError.

Previous « Waits Next Dialogs »