R: Does code return a visible or invisible object?

expect_invisible {testthat} | R Documentation

## Does code return a visible or invisible object?

### Description

Use this to test whether a function returns a visible or invisible output. Typically you'll use this to check that functions called primarily for their side-effects return their data argument invisibly.

### Usage

    expect_invisible(call, label = NULL)

    expect_visible(call, label = NULL)

### Arguments

`call` | A function call.
`label` | Used to customise failure messages. For expert use only.

### Value

The evaluated `call`, invisibly.

### Examples

    expect_invisible(x <- 10)
    expect_visible(x)

    # Typically you'll assign the result of the expectation so you can
    # also check that the value is as you expect.
    greet <- function(name) {
      message("Hi ", name)
      invisible(name)
    }
    out <- expect_invisible(greet("Hadley"))
    expect_equal(out, "Hadley")

[Package testthat version 3.0.1 Index]