Merge runfiles from transitive dependencies of rust_test crate attr

rust/private/rustc.bzl

@@ -1268,6 +1268,9 @@ def rustc_compile_action(
         files = getattr(ctx.files, "data", []) + coverage_runfiles,
         collect_data = True,
     )
+    if getattr(ctx.attr, "crate", None):
+        runfiles = runfiles.merge(ctx.attr.crate[DefaultInfo].default_runfiles)
+        runfiles = runfiles.merge(ctx.attr.crate[DefaultInfo].data_runfiles)
 
     # TODO: Remove after some resolution to
     # https://github.com/bazelbuild/rules_rust/issues/771

test/rust/BUILD.bazel

@@ -8,7 +8,9 @@ rust_library(
         "src/greeter.rs",
         "src/lib.rs",
     ],
+    data = ["greeting.txt"],
     edition = "2018",
+    deps = ["//tools/runfiles"],
 )
 
 rust_binary(

test/rust/greeting.txt

@@ -0,0 +1 @@
+Welcome

test/rust/src/greeter.rs

@@ -34,6 +34,23 @@ impl Greeter {
         }
     }
 
+    /// Constructs a new `Greeter` with greeting defined in txt file
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hello_lib::greeter::Greeter;
+    ///
+    /// let greeter = Greeter::from_txt_file()?;
+    /// ```
+    pub fn from_txt_file() -> std::io::Result<Greeter> {
+        Ok(Greeter {
+            greeting: std::fs::read_to_string(
+                runfiles::Runfiles::create()?.rlocation("rules_rust/test/rust/greeting.txt"),
+            )?,
+        })
+    }
+
     /// Returns the greeting as a string.
     ///
     /// # Examples
@@ -72,4 +89,10 @@ mod test {
         let hello = Greeter::new("Hi");
         assert_eq!("Hi Rust", hello.greeting("Rust"));
     }
+
+    #[test]
+    fn test_greeting_from_txt_file() {
+        let welcome = Greeter::from_txt_file().unwrap();
+        assert_eq!("Welcome Rust", welcome.greeting("Rust"));
+    }
 }