The files in source_files are first sourced into a new environment
to define functions to be checked. Then they are instrumented to track
coverage and the files in test_files are sourced.
file_coverage(source_files, test_files, line_exclusions = NULL,
function_exclusions = NULL, parent_env = parent.frame())Character vector of source files with function definitions to measure coverage
Character vector of test files with code to test the functions
a named list of files with the lines to exclude from each file.
a vector of regular expressions matching function
names to exclude. Example print\. to match print methods.
The parent environment to use when sourcing the files.