Type Coverage

Type coverage reports how much of the PHP code has types. The elements that can be typed are:

• Arguments in methods

• Return type

• Properties

• Class constants

Some elements cannot be typed:

• Arrays

• Lexical variables

• Yield values

• Local variables.

Type coverage is used as a metrics, to ensure that every line of code is used at least once during the tests. While it is a necessary feature, this is not always sufficient to ensure that the application is well tested, as lines of code are reused in several situations, and would require multiple tests.

<?php

    function foo($i = 0) : int {
        return $i + 1;
    }

?>

See also How to Measure Your Type Coverage, phpunit/php-code-coverage and PHP code coverage tool.

Related : Type System, Coverage, Analysis, Type Checking, Type Inference

Related packages : tomasvotruba/type-coverage