Change test execution directory in Bazel? - bazel

Question

I have a simple Bazel project layout like this:
.
├── foo
│   ├── BUILD.bazel
│   ├── testdata
│   │   └── a.txt
│   └── test.sh
└── WORKSPACE
The test checks that a.txt exists:
foo/test.sh
#!/bin/bash
FILE=foo/testdata/a.txt
test -f "$FILE"
And it is defined for Bazel like this:
foo/BUILD.bazel
sh_test(
name = "foo",
size = "small",
srcs = [ "test.sh" ],
data = glob([ "testdata/*.txt" ]),
)
However, suppose I don't want my test to depend on its location within the workspace:
#!/bin/bash
FILE=testdata/a.txt # <-------- Path relative to the package directory
test -f "$FILE"
This does not work of course.
$ bazel test --cache_test_results=no --test_output=streamed //foo
...
//foo:foo FAILED in 0.0s
Is there a way to define my test target in Bazel so that it works, without modifying my test script?
In case it matters:
$ bazel --version
bazel 5.3.1

Answer 1

Bazel expects the files to be relative to the WORKSPACE file. Therefore, somewhere the path has to be stored. For instance, you can move the path from .sh file to BUILD file:
Add Skylib to your project, i.e. extend you WORKSPACE file:
WORKSPACE
load("#bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "bazel_skylib",
sha256 = "74d544d96f4a5bb630d465ca8bbcfe231e3594e5aae57e1edbf17a6eb3ca2506",
urls = [
"https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.3.0/bazel-skylib-1.3.0.tar.gz",
"https://github.com/bazelbuild/bazel-skylib/releases/download/1.3.0/bazel-skylib-1.3.0.tar.gz",
],
)
load("#bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
bazel_skylib_workspace()
Replace the path in the bash script using text replacement:
foo/BUILD.bazel
load("#bazel_skylib//rules:expand_template.bzl", "expand_template")
expand_template(
name = "modifiy_for_bazel",
out = "test_modfied_for_bazel.sh",
substitutions = {
"FILE=testdata/a.txt": "FILE=foo/testdata/a.txt",
},
template = "test.sh",
)
sh_test(
name = "foo",
size = "small",
srcs = ["test_modfied_for_bazel.sh"],
data = glob(["testdata/*.txt"]),
)
Now bazel test --cache_test_results=no --test_output=streamed //foo works.
A similar problem is described here: Bazel: Reading a file with relative path to package, not workspace