[CALCITE-7261] DiffRepository generation xml does not respect alphabetical order

testkit/src/main/java/org/apache/calcite/test/DiffRepository.java

@@ -586,7 +586,7 @@ private synchronized void update(
     int i = 0;
     final List<String> names = Pair.left(map);
     for (String s : names) {
-      if (s.compareToIgnoreCase(testCaseName) <= 0) {
+      if (s.compareTo(testCaseName) <= 0) {
         ++i;
       }
     }
@@ -598,13 +598,13 @@ private synchronized void update(
     // will end up in exactly the right position, and if the list is not sorted,
     // the new item will end up in approximately the right position.
     while (i < map.size()
-        && names.get(i).compareToIgnoreCase(testCaseName) < 0) {
+        && names.get(i).compareTo(testCaseName) < 0) {
       ++i;
     }
-    if (i >= map.size() - 1) {
+    if (i > map.size() - 1) {
       return null;
     }
-    while (i >= 0 && names.get(i).compareToIgnoreCase(testCaseName) > 0) {
+    while (i >= 0 && names.get(i).compareTo(testCaseName) > 0) {
       --i;
     }
     return map.get(i + 1).right;

testkit/src/test/java/org/apache/calcite/test/DiffRepositoryGeneratedFileTest.java

@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.calcite.test;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.endsWith;
+
+/**
+ * Tests checking generated actual XML version.
+ *
+ * <p>Test case for
+ * <a href="https://issues.apache.org/jira/browse/CALCITE-7261">[CALCITE-7261]
+ * DiffRepository generation xml doesn't respect alphabetical order</a>.
+ */
+public class DiffRepositoryGeneratedFileTest {
+  private static final DiffRepository REPO =
+      DiffRepository.lookup(DiffRepositoryGeneratedFileTest.class);
+
+  @AfterAll
+  static void tearDown() throws IOException {
+    final String fileContent =
+        String.join("\n", Files.readAllLines(Paths.get(REPO.logFilePath())));
+    assertThat(
+        fileContent, endsWith(
+            "<Root>\n"
+            +  "  <TestCase name=\"testDiff\">\n"
+            +  "    <Resource name=\"resource\">\n"
+            +  "      <![CDATA[diff]]>\n"
+            +  "    </Resource>\n"
+            +  "  </TestCase>\n"
+            +  "  <TestCase name=\"testNull\">\n"
+            +  "    <Resource name=\"resource\">\n"
+            +  "      <![CDATA[null]]>\n"
+            +  "    </Resource>\n"
+            +  "  </TestCase>\n"
+            +  "  <TestCase name=\"testmulti\">\n"
+            +  "    <Resource name=\"resource\">\n"
+            +  "      <![CDATA[multi]]>\n"
+            +  "    </Resource>\n"
+            +  "  </TestCase>\n"
+            +  "</Root>"));
+  }
+
+  @Test void testDiff() {
+    REPO.set("resource", "diff");
+  }
+
+  // Here method name was intentionally written in lower case to highlight
+  // discrepancy between checking logic and generated logic
+  @Test void testmulti() {
+    REPO.set("resource", "multi");
+  }
+
+  @Test void testNull() {
+    REPO.set("resource", "null");
+  }
+}

testkit/src/test/resources/org/apache/calcite/test/DiffRepositoryGeneratedFileTest.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" ?>
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to you under the Apache License, Version 2.0
+  ~ (the "License"); you may not use this file except in compliance with
+  ~ the License.  You may obtain a copy of the License at
+  ~
+  ~ http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<Root></Root>