feat: add `rules_diff@1.0.0-alpha.3` (#1513)

Brings two rules:

- `diff_file_test`
- `diff_directory_test`

Uses `diff` from `ape` so is hermetic and consistent across operating
systems, even Windows.

Negates the non-hermetic-ness of `bazel_skylib#diff_test` that uses
`diff` from the system.

A new module for `diff` related rules makes sense, in the future we may
want to enable a three file comparison rule with `diff3`, byte-by-byte
comparison with `cmp` or other possible differencing rules.

This module also exposes the hermetic toolchains for use in other
modules:

- `@rules_diff//diff/toolchain/diff:type`
- `@rules_diff//diff/toolchain/diff3:type`
- `@rules_diff//diff/toolchain/sdiff:type`
- `@rules_diff//diff/toolchain/cmp:type`

At this time, we're in alpha as the rules need to be fleshed out and
tested in more situations. For example, we are not fully testing with
all possible combinations of runfiles.

4 files changed, 74 insertions, 0 deletions

diff --git a/modules/rules_diff/1.0.0-alpha.3/MODULE.bazel b/modules/rules_diff/1.0.0-alpha.3/MODULE.bazel
new file mode 100644
index 0000000..6072f42
--- /dev/null
+++ b/modules/rules_diff/1.0.0-alpha.3/MODULE.bazel
@@ -0,0 +1,33 @@
+module(
+    name = "rules_diff",
+    version = "1.0.0-alpha.3",
+    bazel_compatibility = [
+        ">=7.0.0",
+    ],
+    compatibility_level = 1,
+)
+
+bazel_dep(name = "toolchain_utils", version = "1.0.0-beta.1")
+bazel_dep(name = "ape", version = "1.0.0-alpha.3")
+
+export = use_extension("@toolchain_utils//toolchain/export:defs.bzl", "toolchain_export")
+
+resolved = use_repo_rule("@toolchain_utils//toolchain/resolved:defs.bzl", "toolchain_resolved")
+
+[
+    (
+        use_repo(export, "ape-{}".format(tool)),
+        export.symlink(
+            name = tool,
+            target = "@ape-{}".format(tool),
+        ),
+        use_repo(export, tool),
+        resolved(
+            name = "resolved-{}".format(tool),
+            toolchain_type = "//diff/toolchain/{}:type".format(tool),
+        ),
+    )
+    for tool in ("diff", "diff3", "sdiff", "cmp")
+]
+
+register_toolchains("//diff/toolchain/...")
diff --git a/modules/rules_diff/1.0.0-alpha.3/presubmit.yml b/modules/rules_diff/1.0.0-alpha.3/presubmit.yml
new file mode 100644
index 0000000..6a22be2
--- /dev/null
+++ b/modules/rules_diff/1.0.0-alpha.3/presubmit.yml
@@ -0,0 +1,20 @@
+bcr_test_module:
+  module_path: e2e
+  matrix:
+    bazel:
+      - 7.x
+    platform:
+      - debian10
+      - ubuntu2004
+      - macos
+      # TODO: we need `ape` to support `macos_arm64`
+      # - macos_arm64
+      # TODO: enable this once the `gitlab.arm.com` certificate is validated on BuildKite runner
+      # - windows
+  tasks:
+    run_tests:
+      name: Run end-to-end Tests
+      bazel: ${{ bazel }}
+      platform: ${{ platform }}
+      test_targets:
+        - "//..."
diff --git a/modules/rules_diff/1.0.0-alpha.3/source.json b/modules/rules_diff/1.0.0-alpha.3/source.json
new file mode 100644
index 0000000..42723a8
--- /dev/null
+++ b/modules/rules_diff/1.0.0-alpha.3/source.json
@@ -0,0 +1,5 @@
+{
+  "url": "https://gitlab.arm.com/bazel/rules_diff/-/releases/v1.0.0-alpha.3/downloads/src.tar.gz",
+  "integrity": "sha512-g8eVWXWcRpkiWjxs54Zua9tjdX/mTZV2yWslBrFqftvHDaCLxJQ1uXb4fRqC3pM1XKFouelMkviYZSMJaVAT8w==",
+  "strip_prefix": "rules_diff-v1.0.0-alpha.3"
+}
diff --git a/modules/rules_diff/metadata.json b/modules/rules_diff/metadata.json
new file mode 100644
index 0000000..c2a3d03
--- /dev/null
+++ b/modules/rules_diff/metadata.json
@@ -0,0 +1,16 @@
+{
+    "homepage": "https://gitlab.arm.com/bazel/rules_diff",
+    "repository": [
+        "https://gitlab.arm.com/bazel/rules_diff"
+    ],
+    "versions":[
+        "1.0.0-alpha.3"
+    ],
+    "maintainers": [
+        {
+            "email": "matthew.clarkson@arm.com",
+            "github": "mattyclarkson",
+            "name": "Matt Clarkson"
+        }
+    ]
+}