Basics

This check has a base priority of normal and works with any version of Elixir.

Explanation

Forbids html =~ "..." assertions in test files.

Asserting that a rendered HTML blob contains a particular string is brittle: any markup change (whitespace, attribute reordering, classname tweak) can flip the test red without the user-visible behaviour having changed. Worse, it tends to test that the string appears somewhere, not that the right element rendered the right text.

Prefer selecting a specific element (by id, data-test, or other stable selector) and asserting via LiveViewTest helpers such as has_element?/3.

The check fires on =~ "string literal" when the left-hand side is one of:

• the bare variable html
• a call to render(...) (e.g. render(view))
• a pipe ending in render(...) (e.g. view |> render())

Other =~ usages (e.g. log =~ "..." against captured logs) are left alone, as is any regex match (html =~ ~r/.../).

Bad

{:ok, view, html} = live(conn, "/users")
assert html =~ "Welcome, Alice"
assert render(view) =~ "Welcome, Alice"
assert view |> render() =~ "Welcome, Alice"

Good

{:ok, view, _html} = live(conn, "/users")
assert has_element?(view, "[data-test=greeting]", "Welcome, Alice")

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.