Expand fixture documentation a little

Author: TimoFreiberg

crates/ra_db/src/fixture.rs

@@ -2,7 +2,7 @@
 //! A fixture without metadata is parsed into a single source file.
 //! Use this to test functionality local to one file.
 //!
-//! Example:
+//! Simple Example:
 //! ```
 //! r#"
 //! fn main() {
@@ -15,7 +15,7 @@
 //! The basic form is specifying filenames,
 //! which is also how to define multiple files in a single test fixture
 //!
-//! Example:
+//! Example using two files in the same crate:
 //! ```
 //! "
 //! //- /main.rs
@@ -29,14 +29,28 @@
 //! "
 //! ```
 //!
+//! Example using two crates with one file each, with one crate depending on the other:
+//! ```
+//! r#"
+//! //- /main.rs crate:a deps:b
+//! fn main() {
+//!     b::foo();
+//! }
+//! //- /lib.rs crate:b
+//! pub fn b() {
+//!     println!("Hello World")
+//! }
+//! "#
+//! ```
+//!
 //! Metadata allows specifying all settings and variables
 //! that are available in a real rust project:
 //! - crate names via `crate:cratename`
 //! - dependencies via `deps:dep1,dep2`
 //! - configuration settings via `cfg:dbg=false,opt_level=2`
 //! - environment variables via `env:PATH=/bin,RUST_LOG=debug`
 //!
-//! Example:
+//! Example using all available metadata:
 //! ```
 //! "
 //! //- /lib.rs crate:foo deps:bar,baz cfg:foo=a,bar=b env:OUTDIR=path/to,OTHER=foo