Error deserialising output of cargo test --doc

[xd009642]

I got the deserialisation message Err(Error("expected value", line: 3, column: 1)) when running parse_messages on the piped output of: cargo +nightly test --message-format json --manifest-path tarpaulin/tests/data/doc_coverage/Cargo.toml --doc

Below is the json (but prettified):

{
   "reason":"compiler-artifact",
   "package_id":"doc_coverage 0.1.0 (path+file:///home/xd009642/code/rust/tarpaulin/tests/data/doc_coverage)",
   "target":{
      "kind":[
         "lib"
      ],
      "crate_types":[
         "lib"
      ],
      "name":"doc_coverage",
      "src_path":"/home/xd009642/code/rust/tarpaulin/tests/data/doc_coverage/src/lib.rs",
      "edition":"2018",
      "doctest":true
   },
   "profile":{
      "opt_level":"0",
      "debuginfo":2,
      "debug_assertions":true,
      "overflow_checks":true,
      "test":false
   },
   "features":[

   ],
   "filenames":[
      "/home/xd009642/code/rust/tarpaulin/tests/data/doc_coverage/target/debug/deps/libdoc_coverage-c0b9eafea90c1625.rlib",
      "/home/xd009642/code/rust/tarpaulin/tests/data/doc_coverage/target/debug/deps/libdoc_coverage-c0b9eafea90c1625.rmeta"
   ],
   "executable":null,
   "fresh":false
}

[ehuss]

I think parse_messages is misleading for how to parse JSON output. At a minimum, it would be best to only parse lines that start with {, like this:

    let mut reader = BufReader::new(command.stdout.unwrap());
    for line in reader.lines() {
        let line = line.unwrap();
        if line.starts_with('{') {
            let message: Message = serde_json::from_str(&line).unwrap();
            println!("{:#?}", message);
        }
    }

Additionally, you may want to scan for lines to stop looking for JSON output. For example, you don't want to continue parsing with cargo run when it starts executing the process. One tool I wrote has "stop lines" that will abort processing, like the regex ^\s*Running . I filed rust-lang/cargo#7978 for improving that.

In this case, test --doc is emitting test results to stdout.

[xd009642]

Ah I see! It would be helpful in this case if --doc also allowed the --no-run option because that's likely how my other usage is working fine

[oli-obk]

We now have a more robust message parsing scheme