[SpannerToSourceDb] Fixing flaky UT and also improving coverage by darshan-sj · Pull Request #3874 · GoogleCloudPlatform/DataflowTemplates

darshan-sj · 2026-06-03T06:18:04Z

Some test cases in SourceWriterFnTest.java‎ were flaky because SourceProcessorFactoryTest was not restoring the static variables of SourceProcessorFactory which it mocked in the tests. Fixed the SourceProcessorFactoryTest and also removed the flaky tests in SourceWriterFnTest since they were not adding much value.
Improved test coverage in other files.

gemini-code-assist · 2026-06-03T06:18:46Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on improving the robustness of the SpannerToSourceDb migration tool by enhancing error handling in DML generation and refactoring factory initialization. Additionally, it significantly increases test coverage by adding comprehensive unit tests for various edge cases in DML generation, type handling, and shadow table creation, ensuring more stable and predictable behavior.

Highlights

Error Handling Improvements: Updated DML generation logic to properly log warnings and return null when schema mapping fails, rather than silently continuing.
Code Refactoring: Refactored SourceProcessorFactory to use static Map.of() for cleaner initialization and improved maintainability.
Test Coverage: Added extensive unit tests for DML generation and type handling to cover edge cases, error scenarios, and improve overall reliability.

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gemini-code-assist

Code Review

This pull request refactors SourceProcessorFactory to use immutable maps for generators, connection helpers, and connection URLs, and updates column mapping logic in CassandraDMLGenerator and DMLGeneratorUtils to log warnings and return null upon mapping failures. It also adds several unit tests for edge cases. However, making connectionHelperMap final and removing its setter prevents tests from mocking connection helpers, resulting in unused local variables in SourceProcessorFactoryTest and potential test flakiness from real connection attempts. Additionally, a duplicate mock setup line was identified in CassandraDMLGeneratorTest.

darshan-sj · 2026-06-03T06:49:13Z

/gemini review

gemini-code-assist

Code Review

This pull request improves error handling and robustness in the Spanner-to-SourceDB template by returning null and logging warnings when Spanner column mappings are missing in CassandraDMLGenerator and DMLGeneratorUtils. It also introduces comprehensive unit tests for these edge cases, type-handling failures, and shadow table creation exceptions, while removing some ignored tests in SourceWriterFnTest. The feedback points out a critical mismatch in the mock timeout duration within the new ShadowTableCreatorTest exception test, which could prevent the mock from being triggered and cause the test to fail.

codecov · 2026-06-03T06:56:09Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.58%. Comparing base (b42fff3) to head (8ecd288).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3874      +/-   ##
============================================
+ Coverage     55.53%   55.58%   +0.04%     
- Complexity     6576     6584       +8     
============================================
  Files          1103     1103              
  Lines         67570    67573       +3     
  Branches       7581     7581              
============================================
+ Hits          37527    37561      +34     
+ Misses        27627    27603      -24     
+ Partials       2416     2409       -7

Components	Coverage Δ
spanner-templates	`88.52% <100.00%> (+0.21%)`	⬆️
spanner-import-export	`68.54% <ø> (+0.01%)`	⬆️
spanner-live-forward-migration	`90.19% <ø> (-0.04%)`	⬇️
spanner-live-reverse-replication	`84.41% <100.00%> (+0.44%)`	⬆️
spanner-bulk-migration	`92.60% <ø> (-0.02%)`	⬇️
gcs-spanner-dv	`88.96% <ø> (-0.04%)`	⬇️

Files with missing lines	Coverage Δ
...2/templates/dbutils/dml/CassandraDMLGenerator.java	`97.04% <100.00%> (+7.16%)`	⬆️
...rt/v2/templates/dbutils/dml/DMLGeneratorUtils.java	`98.11% <100.00%> (+10.49%)`	⬆️
...ates/dbutils/processor/SourceProcessorFactory.java	`81.94% <100.00%> (+0.25%)`	⬆️

... and 9 files with indirect coverage changes

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❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
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darshan-sj · 2026-06-03T06:59:18Z

/gemini review

gemini-code-assist

Code Review

This pull request improves error handling in CassandraDMLGenerator and DMLGeneratorUtils by logging warnings and returning null when Spanner columns are missing from the schema mapping. It also adds extensive unit tests covering these edge cases, type handling exceptions, and shadow table creation errors, while cleaning up unused imports and ignored tests. The review feedback suggests dynamically backing up and restoring the connection helper map in SourceProcessorFactoryTest instead of hardcoding it, which prevents the tests from becoming fragile when new database types are introduced.

darshan-sj · 2026-06-03T07:10:40Z

/gemini review

gemini-code-assist

Code Review

This pull request improves error handling in CassandraDMLGenerator and DMLGeneratorUtils by logging warnings and returning null when a Spanner column name is not found in the schema mapping. It also introduces a package-private getter in SourceProcessorFactory to facilitate saving and restoring static state in tests, cleans up unused imports and ignored tests in SourceWriterFnTest, and adds comprehensive unit tests across several test files. Feedback is provided on SourceProcessorFactory to return an unmodifiable map from getConnectionHelperMap() to prevent accidental modifications of internal static state.

shreyakhajanchi · 2026-06-04T06:32:12Z

+    PreparedStatementGeneratedResponse prepResponse = (PreparedStatementGeneratedResponse) response;
+
+    assertTrue(prepResponse.getDmlStatement().contains("\"LastName\""));
+    assertTrue(!prepResponse.getDmlStatement().contains("\"MissingCol\""));


better to use assertFalse here for readbility

shreyakhajanchi · 2026-06-04T06:52:08Z

        spannerColName = schemaMapper.getSpannerColumnName("", sourceTable.name(), sourceColName);
      } catch (NoSuchElementException e) {
-        continue;
+        LOG.warn(


I think we should restore this change , what if there are 2 pks in mysql , 1 in spanner and the 2nd one in mysql has default set , then the insert statement would be perfectly valid, i tested:

create table test1(id int, id1 int default 1, name varchar(1000), PRIMARY key (id,id1)); insert into test1(id) values (1);

shreyakhajanchi · 2026-06-04T06:56:18Z

+    when(sourceTable.name()).thenReturn("src_table");
+
+    when(schemaMapper.getSpannerColumnName("", "src_table", "col1"))
+        .thenThrow(new java.util.NoSuchElementException("Not found"));


please use imports: java.util.NoSuchElementException

shreyakhajanchi · 2026-06-04T06:57:33Z

+  }
+
+  @Test
+  public void testGetPkColumnValues_SpannerColDefNull() {


actually when the column definition null it should be treated same as NoSuchElementException which means we should skip this column. Thoughts?

darshan-sj requested a review from a team as a code owner June 3, 2026 06:18

darshan-sj requested review from jsuhani-2026 and manitgupta June 3, 2026 06:18

pull-request-size Bot added the size/XL label Jun 3, 2026

gemini-code-assist Bot reviewed Jun 3, 2026

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darshan-sj force-pushed the reverse-ut-1 branch 2 times, most recently from d19b1e6 to e647fa5 Compare June 3, 2026 06:28

[SpannerToSourceDb] Fixing flaky UT and also improving coverage

519f489

darshan-sj force-pushed the reverse-ut-1 branch from e647fa5 to 519f489 Compare June 3, 2026 06:43

darshan-sj added the ignore-for-release label Jun 3, 2026

gemini-code-assist Bot reviewed Jun 3, 2026

View reviewed changes

Comment thread ...rcedb/src/test/java/com/google/cloud/teleport/v2/templates/utils/ShadowTableCreatorTest.java

Addressing comment

dcf33cc

gemini-code-assist Bot reviewed Jun 3, 2026

View reviewed changes

Comment thread ...ava/com/google/cloud/teleport/v2/templates/dbutils/processor/SourceProcessorFactoryTest.java

Addressing comments

8ecd288

gemini-code-assist Bot reviewed Jun 3, 2026

View reviewed changes

Comment thread ...in/java/com/google/cloud/teleport/v2/templates/dbutils/processor/SourceProcessorFactory.java

shreyakhajanchi reviewed Jun 4, 2026

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darshan-sj commented Jun 3, 2026 •

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