R: Check if an argument is NULL

checkNull {checkmate} | R Documentation

## Check if an argument is NULL

### Description

Check if an argument is NULL

### Usage

    checkNull(x)

    check_null(x)

    assertNull(x, .var.name = vname(x), add = NULL)

    assert_null(x, .var.name = vname(x), add = NULL)

    testNull(x)

    test_null(x)

### Arguments

`x` | [any] Object to check.
`.var.name` | [`character(1)`] Name of the checked object to print in assertions. Defaults to the heuristic implemented in `vname`.
`add` | [`AssertCollection`] Collection to store assertion messages. See `AssertCollection`.

### Value

Depending on the function prefix: If the check is successful, the functions `assertNull`/`assert_null` return `x` invisibly, whereas `checkNull`/`check_null` and `testNull`/`test_null` return `TRUE`. If the check is not successful, `assertNull`/`assert_null` throws an error message, `testNull`/`test_null` returns `FALSE`, and `checkNull` returns a string with the error message. The function `expect_null` always returns an `expectation`.

### See Also

Other basetypes: `checkArray`, `checkAtomicVector`, `checkAtomic`, `checkCharacter`, `checkComplex`, `checkDataFrame`, `checkDate`, `checkDouble`, `checkEnvironment`, `checkFactor`, `checkFormula`, `checkFunction`, `checkIntegerish`, `checkInteger`, `checkList`, `checkLogical`, `checkMatrix`, `checkNumeric`, `checkPOSIXct`, `checkRaw`, `checkVector`

### Examples

    testNull(NULL)
    testNull(1)

[Package checkmate version 1.9.4 Index]