tests/testthat/test-appender.R

In logger: A Lightweight, Modern and Flexible Logging Utility

library(logger)
library(testthat)

## save current settings so that we can reset later
threshold <- log_threshold()
layout    <- log_layout()
appender  <- log_appender()

context('appenders')

test_that('append to file', {
    log_layout(layout_glue_generator('{level} {msg}'))
    log_threshold(TRACE)
    t <- tempfile()
    log_appender(appender_file(t))
    log_info('foobar')
    log_info('{1:2}')
    expect_equal(length(readLines(t)), 3)
    expect_equal(readLines(t)[1], 'INFO foobar')
    expect_equal(readLines(t)[3], 'INFO 2')
    unlink(t)
    rm(t)
})

test_that('overwrite file', {
    log_layout(layout_glue_generator('{level} {msg}'))
    log_threshold(TRACE)
    t <- tempfile()
    log_appender(appender_file(t, append = FALSE))
    log_info('foobar')
    log_info('{1:2}')
    expect_equal(length(readLines(t)), 2)
    expect_equal(readLines(t), c('INFO 1', 'INFO 2'))
    log_info('42')
    expect_equal(length(readLines(t)), 1)
    expect_equal(readLines(t), 'INFO 42')
    unlink(t)
    rm(t)
})

test_that('append to file + print to console', {
    t <- tempfile()
    log_appender(appender_tee(t))
    expect_equal(capture.output(log_info('foobar'), type = 'message'), 'INFO foobar')
    devnull <- capture.output(log_info('{1:2}'), type = 'message')
    expect_equal(length(readLines(t)), 3)
    expect_equal(readLines(t)[1], 'INFO foobar')
    unlink(t)
    rm(t)
})

test_that('logrotate', {
    log_layout(layout_glue_generator('{msg}'))
    log_threshold(TRACE)
    t <- tempfile()
    dir.create(t)
    f <- file.path(t, 'log')
    log_appender(appender_file(f, max_lines = 2, max_files = 5L))
    for (i in 1:24) log_info(i)
    expect_equal(length(readLines(f)), 2)
    expect_equal(length(list.files(t)), 5)
    expect_equal(readLines(f), c('23', '24'))
    log_info('42')
    expect_equal(length(readLines(f)), 1)
    expect_equal(readLines(f), '42')
    unlink(t)
    rm(t)
})

## reset settings
log_threshold(threshold)
log_layout(layout)
log_appender(appender)