[sdk generation pipeline] Fix changelog duplication when re-generating management plane SDK

eng/tools/azure-sdk-tools/packaging_tools/sdk_update_version.py

@@ -175,13 +175,43 @@ def edit_version_file(content: list[str]):
     def edit_changelog_file(content: list[str]):
         nonlocal unchanged
         version_line = f"## {version} ({release_date})\n"
+        first_version_index = -1
         for i in range(0, len(content)):
             if re.match(r"^## \d+\.\d+\.\d+(b\d+)?", content[i]):
                 content[i] = version_line
                 unchanged = False
+                first_version_index = i
                 _LOGGER.info(f"Updated version line in CHANGELOG.md to: {version_line.strip()}")
                 break
 
+        # Remove duplicate version section: if a later section has the same version,
+        # delete it (from its header up to the next version header or end of file).
+        # This handles re-generation where the same changelog content is inserted again.
+        if first_version_index >= 0:
+            # Capture the version token from each version header (e.g., "1.2.3" or "1.2.3b1").
+            version_pattern = re.compile(r"^## (?P<ver>\d+\.\d+\.\d+(b\d+)?)")
+            duplicate_start = -1
+            for j in range(first_version_index + 1, len(content)):
+                match = version_pattern.match(content[j])
+                if match:
+                    # Compare only the version token, ignoring the release date or other suffixes.
+                    if match.group("ver") == version:
+                        duplicate_start = j
+                    break  # stop at the next version header regardless
+
+            if duplicate_start >= 0:
+                # Find end of the duplicate section (next version header or EOF)
+                duplicate_end = len(content)
+                for k in range(duplicate_start + 1, len(content)):
+                    if version_pattern.match(content[k]):
+                        duplicate_end = k
+                        break
+                _LOGGER.info(
+                    f"Removing duplicate version section for {version} "
+                    f"(lines {duplicate_start + 1}-{duplicate_end})"
+                )
+                del content[duplicate_start:duplicate_end]
+
     modify_file(str(changelog_path), edit_changelog_file)
     if unchanged:
         _LOGGER.warning(f"No version line found in {changelog_path} to update.")

eng/tools/azure-sdk-tools/tests/test_sdk_update_version.py

@@ -265,3 +265,95 @@ def mock_log_failed_message(message: str, enable_log_error: bool):
     assert (
         log_level is None
     ), "Expected no error log for invalid changelog content in ARM SDK when version is explicitly provided"
+
+
+def test_duplicate_version_section_removed(temp_package):
+    """When re-generating an SDK, the changelog may end up with duplicate version sections.
+    The update_version_main should detect and remove the duplicate. (GitHub issue #12425)"""
+    pkg = temp_package
+    (pkg / "_version.py").write_text('VERSION = "1.1.0b2"\n')
+
+    # Simulate re-generation: changelog has a new section (with placeholder version)
+    # followed by an existing section with the same content and version.
+    changelog_content = (
+        "# Release History\n"
+        "\n"
+        "## 0.0.0 (UnReleased)\n"
+        "\n"
+        "### Features Added\n"
+        "\n"
+        "  - Model `Client` added parameter `setting` in method `__init__`\n"
+        "\n"
+        "### Breaking Changes\n"
+        "\n"
+        "  - Model `StorageProperties` deleted property `iops`\n"
+        "\n"
+        "## 1.1.0b2 (2025-10-08)\n"
+        "\n"
+        "### Features Added\n"
+        "\n"
+        "  - Model `Client` added parameter `setting` in method `__init__`\n"
+        "\n"
+        "### Breaking Changes\n"
+        "\n"
+        "  - Model `StorageProperties` deleted property `iops`\n"
+        "\n"
+        "## 1.1.0b1 (2025-09-01)\n"
+        "\n"
+        "### Other Changes\n"
+        "\n"
+        "  - Initial version\n"
+    )
+    (pkg / "CHANGELOG.md").write_text(changelog_content)
+
+    package_result = {
+        "version": "1.1.0b2",
+        "tagIsStable": False,
+        "targetReleaseDate": "2025-10-08",
+        "changelog": {"content": "### Features Added\n\n  - Model `Client` added parameter `setting`"},
+    }
+    update_version_main(pkg, package_result=package_result)
+
+    result = (pkg / "CHANGELOG.md").read_text()
+    # The duplicate '## 1.1.0b2' section should be removed
+    assert result.count("## 1.1.0b2") == 1, f"Expected exactly one '## 1.1.0b2' section, got:\n{result}"
+    # The older version section should still be present
+    assert "## 1.1.0b1 (2025-09-01)" in result
+    assert "  - Initial version" in result
+
+
+def test_no_duplicate_version_left_intact(temp_package):
+    """When there is no duplicate, the changelog should remain unchanged aside from the version line update."""
+    pkg = temp_package
+    (pkg / "_version.py").write_text('VERSION = "1.0.0b1"\n')
+
+    changelog_content = (
+        "# Release History\n"
+        "\n"
+        "## 0.0.0 (UnReleased)\n"
+        "\n"
+        "### Features Added\n"
+        "\n"
+        "  - New feature\n"
+        "\n"
+        "## 1.0.0b1 (2025-09-01)\n"
+        "\n"
+        "### Other Changes\n"
+        "\n"
+        "  - Initial version\n"
+    )
+    (pkg / "CHANGELOG.md").write_text(changelog_content)
+
+    package_result = {
+        "version": "1.0.0b1",
+        "tagIsStable": False,
+        "targetReleaseDate": "2025-10-08",
+        "changelog": {"content": "### Features Added\n\n  - New feature"},
+    }
+    update_version_main(pkg, package_result=package_result)
+
+    result = (pkg / "CHANGELOG.md").read_text()
+    # Version should be updated to b2
+    assert "## 1.0.0b2" in result
+    # Old b1 section should still exist (it's a different version, not a duplicate)
+    assert "## 1.0.0b1 (2025-09-01)" in result