Remove testing libraries from production environments

[Copilot]

This PR addresses the issue of testing libraries being included in production builds, which unnecessarily increases binary size.

Problem

The github.com/stretchr/testify library was being imported by non-test files, causing it to be included in production builds even though it's only needed for testing.

Changes Made

1. Renamed test utility files to follow Go conventions

• block/test_utils.go → block/test_utils_test.go
• execution/evm/test_helpers.go → execution/evm/test_helpers_test.go

Files with the _test.go suffix are automatically excluded from production builds by the Go compiler.

2. Added build tags to exclude mock files from production

• Added //go:build test tag to da/internal/mocks/da.go

This ensures mock files are only included when building with the test tag.

Verification

Production builds no longer include testify:

# Production build works without testify
go build ./...

# Verify no testify imports in production code
go mod why github.com/stretchr/testify
# Output: (main module does not need package github.com/stretchr/testify)

Tests continue to work:

# Regular tests pass
go test ./...

# DA module tests with mocks
cd da && go test -tags=test ./...

Impact

• Reduced binary size: Testing libraries are excluded from production builds
• Clean separation: Clear distinction between test and production code
• No breaking changes: All existing tests continue to pass
• Development workflow preserved: No impact on testing or development

The mock files in the test/ directory are naturally excluded from production builds due to their location, while the renamed utility files and tagged mock files ensure complete separation of test dependencies from production code.

Fixes #2350.

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[github-actions]

The latest Buf updates on your PR. Results from workflow CI and Release / buf-check (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	⏩ skipped	✅ passed	✅ passed	Jun 27, 2025, 2:23 AM

[tac0turtle]

the goal of this issue is to remove tc "github.com/testcontainers/testcontainers-go/modules/compose" from the production path. its not super urgent but this pr doesnt do that