Package Layout
Cargo uses conventions for file placement to make it easy to dive into a new Cargo package:
.
├── Cargo.lock
├── Cargo.toml
├── src/
│   ├── lib.rs
│   ├── main.rs
│   └── bin/
│       ├── named-executable.rs
│       ├── another-executable.rs
│       └── multi-file-executable/
│           ├── main.rs
│           └── some_module.rs
├── benches/
│   ├── large-input.rs
│   └── multi-file-bench/
│       ├── main.rs
│       └── bench_module.rs
├── examples/
│   ├── simple.rs
│   └── multi-file-example/
│       ├── main.rs
│       └── ex_module.rs
└── tests/
    ├── some-integration-tests.rs
    └── multi-file-test/
        ├── main.rs
        └── test_module.rs
- Cargo.tomland- Cargo.lockare stored in the root of your package (package root).
- Source code goes in the srcdirectory.
- The default library file is src/lib.rs.
- The default executable file is src/main.rs.- Other executables can be placed in src/bin/.
 
- Other executables can be placed in 
- Benchmarks go in the benchesdirectory.
- Examples go in the examplesdirectory.
- Integration tests go in the testsdirectory.
If a binary, example, bench, or integration test consists of multiple source
files, place a main.rs file along with the extra modules
within a subdirectory of the src/bin, examples, benches, or tests
directory. The name of the executable will be the directory name.
You can learn more about Rust’s module system in the book.
See Configuring a target for more details on manually configuring targets. See Target auto-discovery for more information on controlling how Cargo automatically infers target names.