feat: add [email protected] (bazelbuild#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.

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/...")

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:
+        - "//..."

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"
+}

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": "[email protected]",
+            "github": "mattyclarkson",
+            "name": "Matt Clarkson"
+        }
+    ]
+}