Building and Testing with Bazel

This directory contains the core files to run studio-main tests using bazel.

Running bazel

Bazel has the concept of a workspace: the root of all your source files. For us, it is where we repo init our source tree. For google3 vets, this is the “google3” directory. In this document we assume the current directory to be the workspace, but note that bazel can be run from anywhere in the tree.

Bazel is checked-in at tools/base/bazel/bazel. To make things easy you might want to link it like this (assuming ~/bin is in $PATH)

ln -s <workspace>/tools/base/bazel ~/bin/bazel

Then no matter where you are in the workspace, bazel will find the right platform-specific binary and run it.

macOS users:_ You may run into a clang error after reinstalling or updating XCode. To resolve this error, clear bazel of previous configurations with the following command:

$ bazel clean --expunge

Running all the tests

The command to run all the bazel tests run by the PSQ is:

bazel test $(<tools/base/bazel/targets)

The test output is typically present in bazel-testlogs/pkg/target/test.xml (or test.log)

To run all the tests found in tools/base:

bazel test //tools/base/...

To run all the tests in the IntelliJ Android plugin:

bazel test //tools/adt/idea/android/...

Note: The file tools/base/bazel/targets contains the up-to-date list of test targets.

To build Studio without running the tests:

bazel build //tools/adt/idea/...

To run a single test:

# when test splitting is used, specify the $moduleName_tests__all target
bazel test //tools/adt/idea/android:intellij.android.core.tests_tests__all --test_filter=AndroidLayoutDomTest --test_output=streamed

To debug a single test, which will open remote debugging:

bazel test //tools/adt/idea/android:intellij.android.core.tests_tests__all --test_filter=AndroidLayoutDomTest --java_debug

Useful Bazel options

• --nocache_test_results may be required if you are trying to re-run a test without changing anything.
• --test_filter=<TestName> to run a specific test (when test splits are not already in use)

Running with coverage

We currently do not use the in-built Bazel coverage support.

To enable a test in coverage runs do the following:

1. If you used java_test, then you need to replace it with coverage_java_test from //tools/base/bazel:coverage.bzl
2. Add the test target to the “all” coverage_report in tools/base/bazel/coverage/BUILD for inclusion in overall coverage
3. (Optional) Create your own coverage_report target in tools/base/bazel/coverage/BUILD for your team/feature

To build a coverage report do: ./tools/base/bazel/coverage/report.sh

BUILD files

BUILD files define a package with a set build and test rules. In order to support Android Studio we created a new kind of rule, that matches an IntelliJ module: the iml_module rule.

Note that we modify these BUILD files manually, so whenever you make a change to an .iml file, its corresponding BUILD file will have to be changed. This should be done using bazel run //tools/base/bazel:iml_to_build. If you create a new .iml file, you must create the corresponding (empty) BUILD file before running iml_to_build.

iml_module

iml_module(name, srcs, test_srcs, exclude, resources, test_resources, deps, test_runtime_deps,
visibility, exports,javacopts, test_data, test_timeout, test_class, test_shard_count, tags)

This rule will generate the targets:

• name: The production library for this module.
• name_testlib: The test library for this module.
• name_tests: The test target to run this module's tests.

Example

iml_module(
    name = "android",
    srcs = ["src/main/java"],
    resources = ["src/main/resources"],
    test_data = glob(["testData/**"]),
    test_resources = ["src/test/resources"],
    test_srcs = ["src/test/java"],
    deps = [
        "//a/module/only/needed/in/tests:name[module, test]",
        "//a/standard/java/dependency:dep",
        "//path/to/libs:junit-4.12[test]",
        "//path/to/module:name[module]",
    ],
)

A major difference with actual iml modules is that in bazel we must specify the files needed to run the tests. These files are known as runfiles and are specified via the test_data attribute. This is essential to determining which test targets need to be run when an arbitrary file has changed.

More details on the implementation of the iml_module rule can be found in docs/iml-module.md.

Circular Dependencies

Just don't. IntelliJ has support for circular dependencies of modules, but we do not use it in our code base.

Fetching new Maven Dependencies

In order to fetch new Maven artifacts into the local Maven repository under //prebuilts/tools/common/m2/, follow these steps:

1. Add the dependency to the artifacts or data section of the local_maven_repository rule in the tools/base/bazel/toplevel.WORKSPACE file.

• If the artifact is needed as a compile or runtime Java dependency in Bazel, then add it to artifacts.

• If the artifact will only be used in tests as data (i.e., passed into maven_repository rules), then add it to data.

2. Use the following script to download the artifacts:

tools/base/bazel/maven/maven_fetch.sh

3. In order to use the new artifact, use @maven//: prefix. If you added your artifact to artifacts, then do not add the artifact version, if you added your artifact to data, then use the artifact version. E.g., @maven//:com.google.guava.guava" (for artifacts) @maven//:com.google.guava.guava_30.1-jre` (for data).

   • The @maven// prefix points to a dynamically generated Bazel-external repository. You can access the generated file at $REPO/bazel-studio-main/external/maven/BUILD.

4. Check-in your new artifact (and any new transitive dependencies) under //prebuilts/tools/common/m2/.

See the toplevel.WORKSPACE file for examples on how to express non-jar dependency types and classifiers (e.g., linux-x86_64).