Crate lcov

Expand description

LCOV tracefile parser/merger/filter in pure Rust.

LCOV is a graphical front-end for coverage testing tool gcov. It collects gcov data for multiple source files and stores them into the file called as “tracefile”.

The purpose of this crate is to operate the LCOV tracefile faster than the original LCOV Perl implementation.

Usage

Add this to your Cargo.toml:

[dependencies]
lcov = "0.8.1"

In this crate, the data structure corresponding to each line of the LCOV tracefile is called “LCOV record” and is represented as Record. Each line of the LCOV tracefile is composed of a string representing a kind of the record, a colon, a comma-separated field list:

<KIND>:<field#0>,<field#1>,...<field#N>

LCOV record kind is represented as a variant of Record or RecordKind. Each fields of an LCOV record are represented as fields of a struct-like variant of Record.

For details of the LCOV tracefile syntax, see the manpage of geninfo.

Examples

Parsing an LCOV tracefile:

use lcov::{Record, RecordKind, Reader};

// `Reader` is an iterator that iterates over `Result<lcov::Record, E>` read from the input buffer.
let mut reader = Reader::open_file("tests/fixtures/report.info")?;

// Collect the read records into a vector.
let records = reader.collect::<Result<Vec<_>, _>>()?;
assert_eq!(records[0], Record::TestName { name: "".into() });
assert_eq!(records[1].kind(), RecordKind::SourceFile);

// Outputs the read records in LCOV tracefile format.
for record in records {
    println!("{}", record);
}

Creating an LCOV report from String:

use lcov::{Reader, Record};

let input = "\
TN:test_name
SF:/path/to/source/file.rs
DA:1,2
DA:3,0
DA:5,6
LF:3
LH:2
end_of_record
";

// `&[u8]` implements `BufRead`, so you can pass it as an argument to `Reader::new`.
let mut reader = Reader::new(input.as_bytes());

let records = reader.collect::<Result<Vec<_>, _>>()?;
assert_eq!(records[0], Record::TestName { name: "test_name".into() });
assert_eq!(records[1], Record::SourceFile { path: "/path/to/source/file.rs".into() });

// Creates an `String` in tracefile format. In this example, it is the same as `input`.
let output = records.into_iter().map(|rec| format!("{}\n", rec)).collect::<String>();
assert_eq!(input, output);

Merging tracefiles:

use lcov::{Record, RecordKind, Report};

// Creates an empty `Report`.
let mut report = Report::new();

// Merges a first file.
report.merge(Report::from_file("tests/fixtures/report.init.info")?)?;

// Merges a second file.
report.merge(Report::from_file("tests/fixtures/report.run.info")?)?;

// Outputs the merge result in LCOV tracefile format.
for record in report.into_records() {
    println!("{}", record);
}