Improve integration test setup (#1427)

Summary of changes:
- Configure Renovate to update AssertJ and fmt-maven-plugin version
  references in patch files and shell scripts any time those
  dependencies are updated in the top-level `pom.xml`.
- Enhance the `--sync` flag such that it also updates the initial patch
  file, avoiding drift due to line shifts.

.renovaterc.json

@@ -3,6 +3,19 @@
   "extends": [
     "helpers:pinGitHubActionDigests"
   ],
+  "customManagers": [
+    {
+      "customType": "regex",
+      "fileMatch": [
+        "^integration-tests/.*(-init\\.patch|\\.sh)$"
+      ],
+      "matchStrings": [
+        "\\b(?<packageName>[a-z0-9_.-]+?:[a-z0-9_.-]+?):(?<currentValue>[^:]+?):[a-zA-Z0-9_-]+\\b",
+        "<version>(?<currentValue>.*?)<!-- Renovate: (?<packageName>.*?) --></version>"
+      ],
+      "datasourceTemplate": "maven"
+    }
+  ],
   "packageRules": [
     {
       "matchPackagePatterns": [

integration-tests/checkstyle-init.patch

@@ -7,7 +7,7 @@
 +    <dependency>
 +      <groupId>org.assertj</groupId>
 +      <artifactId>assertj-core</artifactId>
-+      <version>${assertj.version}</version>
++      <version>3.26.3<!-- Renovate: org.assertj:assertj-bom --></version>
 +      <scope>test</scope>
 +    </dependency>
      <dependency>

integration-tests/checkstyle.sh

@@ -6,8 +6,7 @@ test_name="$(basename "${0}" .sh)"
 project='checkstyle'
 repository='https://github.com/checkstyle/checkstyle.git'
 revision='checkstyle-10.20.1'
-# XXX: Configure Renovate to manage the AssertJ version declared here.
-additional_build_flags='-Perror-prone-compile,error-prone-test-compile -Dassertj.version=3.24.2 -Dmaven.compiler.failOnError=true'
+additional_build_flags='-Perror-prone-compile,error-prone-test-compile -Dmaven.compiler.failOnError=true'
 additional_source_directories='${project.basedir}${file.separator}src${file.separator}it${file.separator}java,${project.basedir}${file.separator}src${file.separator}xdocs-examples${file.separator}java'
 patch_error_prone_flags=''
 validation_error_prone_flags=''
@@ -33,4 +32,4 @@ fi
   "${patch_error_prone_flags}" \
   "${validation_error_prone_flags}" \
   "${validation_build_flags}" \
-  $@
+  ${@}

integration-tests/run-integration-test.sh

@@ -62,11 +62,7 @@ shared_build_flags="
   ${additional_build_flags}
   "
 
-# XXX: Configure Renovate to manage the fmt-maven-plugin version declared here.
-# XXX: Once GitHub actions uses Maven 3.9.2+, we can inline this variable with
-# version reference `${fmt.version}`, and `-Dfmt.version=2.21.1` added to
-# `shared_build_flags`.
-format_goal='com.spotify.fmt:fmt-maven-plugin:2.21.1:format'
+format_goal='com.spotify.fmt:fmt-maven-plugin:2.25:format'
 
 error_prone_shared_flags='-XepExcludedPaths:(\Q${project.basedir}${file.separator}src${file.separator}\E(it|test|xdocs-examples)\Q${file.separator}resources\E|\Q${project.build.directory}${file.separator}\E).*'
 
@@ -124,14 +120,22 @@ pushd "${project_root}"
 git config user.email || git config user.email '[email protected]'
 git config user.name || git config user.name 'Integration Test'
 
-# Prepare the code for analysis by (a) applying the minimal set of changes
-# required to run Error Prone with Error Prone Support and (b) formatting the
-# code using the same method by which it will be formatted after each
-# compilation round. The initial formatting operation ensures that subsequent
-# modifications can be rendered in a clean manner.
+# Prepare the code for analysis by applying the minimal set of changes required
+# to run Error Prone with Error Prone Support.
+initial_patch="${integration_test_root}/${test_name}-init.patch"
 git clean -fdx
-git apply < "${integration_test_root}/${test_name}-init.patch"
+git apply < "${initial_patch}"
 git commit -m 'dependency: Introduce Error Prone Support' .
+if [ -n "${do_sync}" ]; then
+  # The initial patch applied successfully, but if it was created against a
+  # different version, then offsets may have changed. Here we update the patch
+  # to exactly match the new state.
+  git diff HEAD~1 | "${grep_command}" -vP '^(diff|index)' > "${initial_patch}"
+fi
+
+# Format the patched code using the same method by which it will be formatted
+# after each compilation round. This initial formatting operation ensures that
+# subsequent modifications can be rendered in a clean manner.
 mvn ${shared_build_flags} "${format_goal}"
 git commit -m 'minor: Reformat using Google Java Format' .
 diff_base="$(git rev-parse HEAD)"