feat: add contract tests and consolidate stream parameter structs (issues #658-661)

[soma-enyi]

Summary

This PR addresses four GitHub issues by adding comprehensive contract tests for edge cases and consolidating duplicate type definitions in the FlowStar streaming contract.

Changes Implemented

Issue #658: Test bump_stream() on Nonexistent Stream

• File: contracts/streaming/src/test_security.rs
• Change: Added test_bump_stream_nonexistent_stream_returns_stream_not_found() test
• Purpose: Validates that calling bump_stream() with a nonexistent stream ID properly returns StreamError::StreamNotFound
• Pattern: Follows established security test patterns for negative-path validation
• Details: Tests the scenario where a stream has either never been created or has expired from persistent storage

Issue #659: Test Batch Creation Rejects Contract as Recipient

• File: contracts/streaming/src/test_batch.rs
• Change: Added test_batch_rejects_contract_as_recipient() test
• Purpose: Ensures create_streams_batch() has the same security guard as create_stream() to prevent the contract itself from being a stream recipient
• Implementation: Creates a batch with one valid stream and one invalid entry (contract as recipient), verifies the entire batch is rejected with StreamError::InvalidRecipient
• Atomicity: Validates that batch validation is atomic — no partial state is created on error
• Security: Prevents accidental or malicious configuration where the contract could be recipient of a stream

Issue #660: Test Batch Creation Rejects Dust/Zero-Rate Streams

• File: contracts/streaming/src/test_batch.rs
• Change: Added test_batch_rejects_dust_stream() test
• Purpose: Validates that batch creation properly rejects streams with dust amounts (where per-second rate becomes zero due to integer division)
• Test Case: Creates a batch with both valid and dust stream entries (100 stroops over 1 year = 0 per second)
• Expected: Batch is rejected with StreamError::RateIsZero before any funds are transferred
• Consistency: Mirrors the existing single-stream dust validation logic adapted for batch operations

Issue #661: Consolidate CreateStreamInput and CreateStreamParams Structs

• File: contracts/streaming/src/lib.rs
• Changes:
  • Removed duplicate CreateStreamInput struct definition (lines 178-192)
  • Updated create_streams_batch() function signature to accept Vec<CreateStreamParams> instead of Vec<CreateStreamInput>
  • Both single-stream and batch-create operations now share the same parameter type
• Consistency: Eliminates redundant struct definitions while maintaining identical functionality
• API Surface: Single-stream and batch APIs are now clearly unified in terms of parameter structure
• Future Evolution: Both APIs can now evolve in lock-step without diverging type definitions

Bonus Fix

• File: contracts/streaming/src/test_features.rs
• Change: Removed duplicate import of Address and Env in line 10
• Issue: Pre-existing duplicate that was causing compilation warnings
• Resolution: Cleaned up to follow Rust import best practices

Files Modified

• contracts/streaming/src/test_security.rs (+14 lines)

  • Added test for bump_stream() edge case

• contracts/streaming/src/test_batch.rs (+71 lines)

  • Added two batch validation tests
  • Updated all CreateStreamInput references to CreateStreamParams

• contracts/streaming/src/lib.rs (-16 lines)

  • Removed duplicate CreateStreamInput struct
  • Updated function signature for create_streams_batch()

• contracts/streaming/src/test_features.rs (-1 line)

  • Removed duplicate import statement

Test Results

All new tests pass successfully:
✅ test_bump_stream_nonexistent_stream_returns_stream_not_found
✅ test_batch_rejects_contract_as_recipient
✅ test_batch_rejects_dust_stream

Validation

• All changes compile without errors
• Existing tests continue to pass (160 passed)
• New security tests validate edge cases properly
• Type consolidation maintains backward compatibility at the contract interface level

Closes #658
Closes #659
Closes #660
Closes #661

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