Make it possible for unit tests to have dev deps (#203)

examples/ffi/rust_calling_c/BUILD

@@ -16,7 +16,7 @@ rust_library(
 
 rust_test(
     name = "matrix_test",
-    deps = [":matrix"],
+    crate = ":matrix",
 )
 
 rust_doc(
@@ -41,7 +41,7 @@ rust_library(
 
 rust_test(
     name = "matrix_dylib_test",
-    deps = [":matrix_dynamically_linked"],
+    crate = ":matrix_dynamically_linked",
 )
 
 rust_doc(

examples/ffi/rust_calling_c/simple/BUILD

@@ -23,5 +23,5 @@ rust_binary(
 
 rust_test(
     name = "simple_test",
-    deps = [":simple_example"],
+    crate = ":simple_example",
 )

examples/fibonacci/BUILD

@@ -14,7 +14,7 @@ rust_library(
 
 rust_test(
     name = "fibonacci_test",
-    deps = [":fibonacci"],
+    crate = ":fibonacci",
 )
 
 rust_benchmark(

examples/hello_lib/BUILD

@@ -47,7 +47,7 @@ rust_library(
 
 rust_test(
     name = "hello_lib_test",
-    deps = [":hello_lib"],
+    crate = ":hello_lib",
 )
 
 rust_test(

examples/hello_out_dir/BUILD

@@ -20,5 +20,5 @@ rust_binary(
 rust_test(
     name = "hello_out_dir_test",
     out_dir_tar = ":repacked_srcs.tar.gz",
-    deps = [":hello_out_dir"],
+    crate = ":hello_out_dir",
 )

examples/per_platform_printer/BUILD

@@ -32,5 +32,5 @@ rust_library(
 
 rust_test(
     name = "printer_test",
-    deps = [":printer"],
+    crate = ":printer",
 )

rust/private/rust.bzl

@@ -15,6 +15,34 @@
 load("@io_bazel_rules_rust//rust:private/rustc.bzl", "CrateInfo", "rustc_compile_action")
 load("@io_bazel_rules_rust//rust:private/utils.bzl", "find_toolchain")
 
+_OLD_INLINE_TEST_CRATE_MSG = """
+--------------------------------------------------------------------------------
+Testing crates with inline `#[cfg(test)]` attributes is now handled with the
+`crate` attribute in `rust_test`:
+
+This means you should migrate from:
+
+```
+rust_test(
+    name = "{name}",
+    deps = ["{dep}"],
+    ...
+)
+```
+
+to the following:
+```
+rust_test(
+    name = "{name}",
+    crate = "{dep}",
+    ...
+```
+
+See https://github.com/bazelbuild/rules_rust/pull/203 for more details
+--------------------------------------------------------------------------------
+
+"""
+
 # TODO(marco): Separate each rule into its own file.
 
 def _determine_output_hash(lib_rs):
@@ -124,19 +152,26 @@ def _rust_test_common(ctx, test_binary):
     """
     toolchain = find_toolchain(ctx)
 
-    if len(ctx.attr.deps) == 1 and len(ctx.files.srcs) == 0:
-        # Target has a single dependency but no srcs. Build the test binary using
-        # the dependency's srcs.
-        parent_crate = ctx.attr.deps[0][CrateInfo]
+    if ctx.attr.crate:
+        # Target is building the crate in `test` config
+        # Build the test binary using the dependency's srcs.
+        crate = ctx.attr.crate[CrateInfo]
         target = CrateInfo(
             name = test_binary.basename,
-            type = parent_crate.type,
-            root = parent_crate.root,
-            srcs = parent_crate.srcs,
-            deps = parent_crate.deps,
+            type = crate.type,
+            root = crate.root,
+            srcs = crate.srcs + ctx.files.srcs,
+            deps = crate.deps + ctx.attr.deps,
             output = test_binary,
-            edition = parent_crate.edition,
+            edition = crate.edition,
         )
+    elif len(ctx.attr.deps) == 1 and len(ctx.files.srcs) == 0:
+        dep = ctx.attr.deps[0].label
+        msg = _OLD_INLINE_TEST_CRATE_MSG.format(
+                name=test_binary.basename,
+                dep=dep if ctx.label.package != dep.package else ":" + dep.name
+              )
+        fail(msg)
     else:
         # Target is a standalone crate. Build the test binary as its own crate.
         target = CrateInfo(
@@ -281,6 +316,18 @@ _rust_library_attrs = {
     ),
 }
 
+_rust_test_attrs = {
+    "crate": attr.label(
+        mandatory = False,
+        doc = _tidy("""
+            Target inline tests declared in the given crate
+
+            These tests are typically those that would be held out under
+            `#[cfg(test)]` declarations.
+        """),
+    ),
+}
+
 rust_library = rule(
     _rust_library_impl,
     attrs = dict(_rust_common_attrs.items() +
@@ -459,7 +506,8 @@ Hello world
 
 rust_test = rule(
     _rust_test_impl,
-    attrs = _rust_common_attrs,
+    attrs = dict(_rust_common_attrs.items() +
+                 _rust_test_attrs.items()),
     executable = True,
     fragments = ["cpp"],
     host_fragments = ["cpp"],
@@ -532,6 +580,18 @@ rust_test(
 
 Run the test with `bazel build //hello_lib:hello_lib_test`.
 
+To run a crate or lib with the `#[cfg(test)]` configuration, handling inline
+tests, you should specify the crate directly like so.
+
+```
+rust_test(
+    name = "hello_lib_test",
+    crate = ":hello_lib",
+    # You may add other deps that are specific to the test configuration
+    deps = ["//some/dev/dep"],
+)
+```
+
 ### Example: `test` directory
 
 Integration tests that live in the [`tests` directory][int-tests], they are

test/chained_direct_deps/BUILD

@@ -27,17 +27,17 @@ rust_library(
 
 rust_test(
     name = "mod1_test",
-    deps = [":mod1"],
+    crate = ":mod1",
 )
 
 rust_test(
     name = "mod2_test",
-    deps = [":mod2"],
+    crate = ":mod2",
 )
 
 rust_test(
     name = "mod3_test",
-    deps = [":mod3"],
+    crate = ":mod3",
 )
 
 rust_doc_test(

test/conflicting_deps/BUILD

@@ -16,7 +16,5 @@ rust_library(
 
 rust_test(
     name = "conflicting_deps_test",
-    deps = [
-        ":conflicting_deps",
-    ],
+    crate = ":conflicting_deps",
 )

test/inline_test_with_deps/dep/BUILD

@@ -0,0 +1,11 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "//rust:rust.bzl",
+    "rust_library",
+)
+
+rust_library(
+    name = "dep",
+    srcs = ["src/lib.rs"],
+)

test/inline_test_with_deps/dep/src/lib.rs

@@ -0,0 +1,4 @@
+/// This exists purely to give us a dep to compile against
+pub fn example_test_dep_fn() -> u32 {
+    1
+}

test/inline_test_with_deps/test/BUILD

@@ -0,0 +1,19 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "//rust:rust.bzl",
+    "rust_library",
+    "rust_test",
+)
+
+rust_library(
+    name = "inline",
+    edition = "2018",
+    srcs = ["src/lib.rs"],
+)
+
+rust_test(
+    name = "inline_test",
+    crate = ":inline",
+    deps = ["//test/inline_test_with_deps/dep"],
+)

test/inline_test_with_deps/test/src/lib.rs

@@ -0,0 +1,15 @@
+#[allow(dead_code)]
+fn multiply(val: u32) -> u32 {
+    val * 100
+}
+
+#[cfg(test)]
+mod tests {
+    use super::multiply;
+    use dep::example_test_dep_fn;
+
+    #[test]
+    fn test() {
+        assert_eq!(100, multiply(example_test_dep_fn()));
+    }
+}

test/inline_test_with_deps/test_with_srcs/BUILD

@@ -0,0 +1,20 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "//rust:rust.bzl",
+    "rust_library",
+    "rust_test",
+)
+
+rust_library(
+    name = "inline",
+    edition = "2018",
+    srcs = ["src/lib.rs"],
+)
+
+rust_test(
+    name = "inline_test",
+    crate = ":inline",
+    srcs = ["src/extra.rs"],
+    deps = ["//test/inline_test_with_deps/dep"],
+)

test/inline_test_with_deps/test_with_srcs/src/extra.rs

@@ -0,0 +1,4 @@
+#[cfg(test)]
+pub(crate) fn extra_test_fn() -> u32 {
+    100
+}

test/inline_test_with_deps/test_with_srcs/src/lib.rs

@@ -0,0 +1,18 @@
+#[allow(dead_code)]
+fn multiply(val: u32) -> u32 {
+    val * 100
+}
+
+#[cfg(test)]
+mod extra;
+
+#[cfg(test)]
+mod tests {
+    use super::{multiply, extra};
+    use dep::example_test_dep_fn;
+
+    #[test]
+    fn test() {
+        assert_eq!(extra::extra_test_fn(), multiply(example_test_dep_fn()));
+    }
+}

tools/runfiles/BUILD

@@ -14,7 +14,7 @@ rust_library(
 rust_test(
     name = "runfiles_test",
     data = ["data/sample.txt"],
-    deps = [":runfiles"],
+    crate = ":runfiles",
 )
 
 rust_doc_test(