As part of our commitment to transparency in Cardano's decentralized governance, we're sharing progress on our Intersect-administrated project: Scalus - DApps Development Platform (EC-0020-25).
Milestone 4 focused on testing capabilities — establishing robust, integrated testing tools to ensure reliability and correctness of smart contracts and applications built with Scalus.
What We Delivered
Testing Guide
The Testing section was expanded with comprehensive documentation covering the full testing workflow:
- TDD/ATDD workflow
- Unit testing / Testkit
- Property-based testing with ScalaCheck helpers for Cardano development
- Boundary testing (advanced guide)
- Debugging
Cardano Node Emulator
A particular emphasis was placed on the Cardano in-process Emulator for JVM and JS/TS — a unique environment for fast scenario-based and test-driven development. The Scalus Emulator validates transactions and executes Plutus scripts, performing both Phase 1 validation (transaction structure, signatures, fees, and value conservation) and Phase 2 validation (Plutus script execution with cost tracking), exactly like the mainnet node.
Our engineering blog post on the JS Emulator led to an invitation to showcase the solution at Cardano Foundation development hours.
Property-Based Testing in Practice
Property-based testing is now demonstrated across multiple real-world examples:
- LinkedList and AMM examples using ScalaCheck generators and property assertions;
- Boundary testing for Auction, Crowdfunding, and Lottery — combining Commands and Scenario patterns to verify contract invariants under randomized conditions.
Advanced Data Structures
A new Advanced Data Structures tutorial series covers authenticated collections with both on-chain and off-chain code:
Each structure was benchmarked and optimised while preserving Aiken compatibility. Scalus also provides a trusted setup with Ethereum KZG ceremony (32768 G1 points, 65 G2 points) for the Bilinear Accumulator.
Rosetta Blueprints — Catalogue Complete
We delivered the final 7 of 21 Rosetta blueprints, completing the full catalogue:
- Decentralized Identity
- Constant-product AMM
- Upgradeable Proxy
- Factory
- Simple Wallet
- Anonymous Data
- Atomic Transactions
Each includes validators, off-chain transaction logic, and tests. The finalised blueprints will be contributed to the "Rosetta Smart Contracts" and "Cardano Blueprint and Ecosystem Monitoring" projects in Milestone 5.
Implementations are available in the Scalus examples repository.
Ledger Rules Framework
The Ledger Framework opens the door for developers building L2 protocols and custom ledger extensions on Cardano. Check it out:
- Ledger framework architecture
- Rules customisation (enable, disable, specific rules)
- Writing new rules
Van Rossem Intra-Era Hard Fork — Ready
Scalus is among the first libraries to provide full support for the Van Rossem intra-era hard fork. The capabilities were used by the IntersectMBO team to test the functionality on SanchoNet.
In preparation for the Q2 2026 hard fork, we shipped the complete set of protocol v11 capabilities:
- Case expressions for built-in types
- New built-ins and native types
- Ledger rules updated for Emulator testing
Ongoing Platform Improvements
Based on community feedback, releases v0.15.0 and v0.15.1 brought significant improvements:
Smart contract syntax — all new builtins for protocol v11, expModInteger (CIP-109), BLS12-381 multiScalarMul (CIP-0109), optimised toData for constant values, improved PlutusV3 match lowering to reduce script size, variadic log function with auto-show diagnostics.
Standard & test library — Pretty typeclass with automatic derivation, Eq.derived for equality, comprehensive scalus-testkit API with EvalTestKit and ScalusTest base classes, JavaScript Emulator for cross-platform testing, HD wallet implementation with BIP-39/BIP32-Ed25519/CIP-1852 support.
Transaction builder — TxBuilder.draft for unbalanced transaction assembly, type-safe UtxoQuery DSL with parallel execution, simplified BlockfrostProvider API, Conway era ledger state rules for staking and governance.
Public releases:
- 0.15.1 (2026-02-13)
- 0.15.0 (2026-02-05)
Complete changelog: GitHub
Why This Matters
With Milestone 4, Scalus delivers what production teams need most: confidence that their code works. The integrated testing framework — from unit tests through property-based testing to full emulator-based scenario validation — means developers can catch bugs before they reach the chain. The completed Rosetta blueprints catalogue provides 21 battle-tested reference implementations, and the advanced data structures unlock sophisticated on-chain patterns like Merkle proofs and bilinear accumulators.
The milestone was reviewed and approved by No Witness Labs as third-party assurer, confirming deliverables align with scope and demonstrating that Intersect's milestone-based funding model works.
Treasury reports can be found in the Intersect Treasury Dashboard.
What's Next
Milestone 5 & 6 will focus on advanced UPLC optimisations & Test data management, delivering on our mission to accelerate end-to-end development cycle and becoming the most complete development solution for the application development on Cardano.
Follow our progress on X (@Scalus3) and X (@lantr_io).
Join Scalus Club for early access and to shape the roadmap.
Questions or feedback? Reach out on Discord or email us at contact@lantr.io.
