fix-tck-issue

Testing & Quality

Analyzes and fixes A2A Transport Compatibility Kit (TCK) issues by understanding the specification, reproducing the failure, implementing the fix, and validating it works.

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Fix A2A TCK Compatibility Issue

Triggers

Issue references TCK, compatibility, or transport-specific behavior
Keywords: "TCK", "compatibility", "HTTP+JSON", "gRPC", "JSON-RPC", "specification", "proto"
Issue mentions transport layer discrepancies

Input

Issue number from a2aproject/a2a-java repository
Optional: A2A spec reference (branch/tag/commit, defaults to main)

Workflow

1. Fetch Issue Details

gh issue view <issue-number> --repo a2aproject/a2a-java --json title,body,labels,url

Parse issue to identify:

Affected transport(s): HTTP+JSON, gRPC, JSON-RPC
Expected behavior from specification
Actual behavior (error message, reproducer)
Specification section references
Spec commit checksum (TCK issues include this in spec URLs)

2. Read Specification (if needed)

TCK issues contain the spec checksum, but reading the spec is helpful if TCK lags behind or for additional context.

Fetch from https://github.com/a2aproject/A2A with specified ref (use checksum from issue or default to main):

specification/grpc/a2a.proto - for proto definitions and HTTP transcoding
docs/specification.md - for detailed protocol requirements

Focus on sections referenced in the issue.

3. Analyze Code

Locate relevant code based on transport:

HTTP+JSON: transport/rest
gRPC: transport/grpc
JSON-RPC: transport/jsonrpc

Identify root cause by comparing:

What the spec says should happen
What the code currently does
Why they differ

Optional: If issue includes a curl/grpcurl reproducer, run it manually to validate the issue is genuine.

4. Determine Affected Transports

CRITICAL: If issue doesn't specify a single transport, you MUST create reproducers for ALL affected transports.

Issue mentions specific transport → Test that one only Issue generic or mentions "all transports" → Test HTTP+JSON, gRPC, AND JSON-RPC

5. Create Temporary Reproducer(s)

Create test in appropriate module. Choose location based on test complexity:

Option A: transport/ modules (Unit Tests)* - Use when:

Testing handler logic directly
Need custom AgentCard configuration (e.g., capability flags)
Simpler to set up specific test conditions
HTTP+JSON → transport/rest/src/test/java/org/a2aproject/sdk/transport/rest/handler/RestHandlerTest.java
gRPC → transport/grpc/src/test/java/org/a2aproject/sdk/transport/grpc/handler/GrpcHandlerTest.java
JSON-RPC → transport/jsonrpc/src/test/java/org/a2aproject/sdk/transport/jsonrpc/handler/JSONRPCHandlerTest.java

Option B: reference/ modules (Integration Tests)* - Use when:

Testing full request/response cycle
Need real server behavior
Testing with standard agent configuration
HTTP+JSON → reference/rest/src/test/java/.../
gRPC → reference/grpc/src/test/java/.../
JSON-RPC → reference/jsonrpc/src/test/java/.../

Reproducer requirements:

Follow the exact scenario from the issue
Use request format per specification (e.g., NO taskId in body for HTTP+JSON)
Be named clearly: test_Issue<number>_Reproducer()
Assert the WRONG behavior that issue reports (should fail)

Example:

@Test
public void test_Issue732_Reproducer() {
    // Per spec: taskId should NOT be in request body for HTTP+JSON
    String requestBody = """
        {
          "id": "my-config-001",
          "url": "https://example.com/webhook"
        }""";

    HTTPRestResponse response = handler.createTaskPushNotificationConfiguration(
        context, "", requestBody, taskId);

    assertEquals(201, response.getStatusCode());
}

6. Run Reproducer(s) - Confirm Failure

CRITICAL: You MUST run the reproducer and see it FAIL before proceeding to fix.

For transport/* modules:

mvn test -Dtest=<TestClass>#test_Issue<number>_Reproducer -pl transport/<transport>

For reference/* modules:

mvn test -Dtest=<TestClass>#test_Issue<number>_Reproducer -pl reference/<transport>

Required verification (DO NOT SKIP):

❌ Test MUST fail with the exact error mentioned in the issue
❌ Error message, status code, or exception type MUST match issue description
❌ If testing multiple transports, ALL reproducers must fail

If reproducer doesn't fail as expected:

STOP - Do not proceed to fix
Reassess understanding of the issue
Check if test conditions match issue scenario
Verify you're testing the right transport/endpoint

Only proceed to step 7 after confirming all reproducers fail correctly.

7. Implement Fix

Make minimal code changes to fix the root cause.

If multiple transports are affected: Fix ALL of them before proceeding to verification.

Common patterns:

Missing path parameter extraction: Add builder.setFieldName(pathParam)
Wrong validation: Adjust validation logic to match spec
Incorrect mapping: Fix proto/domain conversion
Wrong error type: Return correct error based on failure reason

8. Run Reproducer(s) - Confirm Fix

Run ALL reproducers you created in step 5.

For transport/* modules:

mvn test -Dtest=<TestClass>#test_Issue<number>_Reproducer -pl transport/<transport>

For reference/* modules:

mvn test -Dtest=<TestClass>#test_Issue<number>_Reproducer -pl reference/<transport>

Required verification:

✅ ALL reproducers must now PASS
✅ Test output shows expected behavior (correct status, no error, etc.)

If any reproducer still fails, debug and refine the fix.

9. Verify Backward Compatibility

Run full test suite for ALL modified transport modules to ensure no regressions:

mvn test -pl transport/rest,transport/jsonrpc,transport/grpc

If you also modified reference modules or only created reproducers there:

mvn test -pl reference/rest,reference/jsonrpc,reference/grpc

All existing tests must pass.

10. Delete Temporary Reproducer(s)

Remove ALL test methods or files created in step 5.

If you added a method to existing test class:

Delete just the test_Issue<number>_Reproducer() method

If you created a new test file:

Delete the entire file (e.g., Issue733ReproducerTest.java)

11. Commit

Add only the impacted files (NOT the temporary reproducers):

git add <changed-files>
git commit -m "fix: <concise description>

<explanation of spec requirement and how code was fixed>

Applied to <list transports if multiple>.

Fixes #<issue-number>"

Example for multi-transport fix:

git add transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java \
        transport/jsonrpc/src/main/java/org/a2aproject/sdk/transport/jsonrpc/handler/JSONRPCHandler.java \
        transport/grpc/src/main/java/org/a2aproject/sdk/transport/grpc/handler/GrpcHandler.java
git commit -m "fix: Return UnsupportedOperationError when capability is disabled

Applied to all three transports: HTTP+JSON, JSON-RPC, and gRPC.

Fixes #733"

Common Root Causes

HTTP+JSON with `body: "*"`

Proto definition with path parameters and body: "*" means:

Path parameters extracted from URL
Body contains remaining fields only
Handler must set path params into builder

Example proto:

rpc CreateTaskPushNotificationConfig(...) {
  option (google.api.http) = {
    post: "/tasks/{task_id}/pushNotificationConfigs"
    body: "*"
  };
}

Fix pattern:

// Extract from URL path and set in builder
builder.setTaskId(taskId);

Field Validation Errors

"X is required" errors often mean:

Field should come from URL path, not body
Handler isn't setting the path parameter
Check proto's HTTP annotation

Test Location Decision Guide

transport/* modules (Unit Tests)

Best for:

Testing handler logic with custom configurations
Issues requiring specific AgentCard capabilities (e.g., streaming=false, extendedAgentCard=false)
Faster test execution
More control over test setup

Test file locations:

transport/rest/src/test/java/org/a2aproject/sdk/transport/rest/handler/RestHandlerTest.java
transport/grpc/src/test/java/org/a2aproject/sdk/transport/grpc/handler/GrpcHandlerTest.java
transport/jsonrpc/src/test/java/org/a2aproject/sdk/transport/jsonrpc/handler/JSONRPCHandlerTest.java

reference/* modules (Integration Tests)