Take it apart.
Make it your own.
39 small projects with real source files. Read the structure, follow the data, and change something.
39 results
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Expense tracker
Track income and expenses using collections and decimal.
Beginner / 02Contact book
Manage contacts with records and search.
Data / 03JSON task manager
Load and save tasks using JSON files.
Algorithms / 04Path finder
Find the shortest path in a grid using BFS.
Data / 05Invoice report
Group paid invoices by customer and render deterministic decimal totals.
Beginner / 06Word frequency
Normalize prepared text and count words with an explicit ordinal comparer.
Data / 07Catalog search
Filter a small product catalog and page a stable result.
Data / 08Task summary
Deserialize a prepared task document, validate its rows, and summarize status.
Beginner / 09Temperature table
Keep conversion logic separate from invariant table formatting.
Algorithms / 10Graph route
Find one shortest route in an unweighted graph using predecessor links.
Async / 11Bounded batch loader
Compose cancellable asynchronous work in small deterministic batches.
Data / 12Inventory audit
Validate product identifiers and quantities before accepting an import.
Memory / 13Audit subscription and cache ownership
Trace two real retaining paths and verify their explicit end boundary without pretending to measure collection.
Memory / 14Encode packets with an owned pooled buffer
Return an independent report from each bounded lease and keep byte lengths separate from pool capacity.
Unity companions / 15Unity health rules companion
A complete console project with seven independent health and lease-reset checks; no UnityEngine dependency.
Unity companions / 16Unity collectathon rules companion
A complete console project testing unique collection, win/timeout terminal states, input bounds and a deterministic run story.
Testing / 17Reservation contract lab
Run independent domain scenarios with a controlled UTC clock and an in-memory notice recorder. This is a console lab, not an installed test framework.
Testing / 18JSON request boundary lab
Check the actual local serializer and independent domain validation against explicit input fixtures. No remote service or full runner is simulated.
I/O & HTTP / 19Build and verify a framed UTF-8 message
Define a versioned byte format with an explicit big-endian length and run twelve independent boundary checks.
I/O & HTTP / 20Verify an offline bounded HTTP importer
Reuse one HttpClient, inject real in-memory HTTP responses, and check nine status, byte-budget and model boundaries.
Unity companions / 21Unity interaction rules companion
A complete portable C# project with 17 independent key, focus, range and invalid-input checks; no UnityEngine dependency.
Current .NET / 22Frozen rate-card contract lab
Build a scalar configuration snapshot with an explicit comparer, then run five independent console checks. No test-framework package is required.
Current .NET / 23Reusable separator tokenizer lab
Use one SearchValues<char> set to split owned nonempty tokens and verify six concrete representation and boundary cases.
Architecture / 24Capacity port contract lab
Run six independent local boundary checks. Files share one console assembly; separate physical dependency enforcement is demonstrated by the external lesson solutions.
Architecture / 25Order acceptance and read-view lab
Check immutable domain input, local identity rejection, event intent, and read snapshots in six console scenarios. The memory adapter is not durable transactional storage.
Load companions / 26Verify bounded admission and draining
Check twelve deterministic ownership boundaries without pretending to benchmark a server.
Load companions / 27Check ledger policy and stable routing
Verify ten policy boundaries in a shared in-memory owner; real process coordination belongs to the external SQLite lab.
ASP.NET companions / 28Check a quote policy independently of HTTP
Verify nine accepted and rejected domain cases before attaching an ASP.NET response adapter.
ASP.NET companions / 29Verify tenant variation and private bypass
Use eight independent checks to keep tenant-specific public keys distinct and private calculations uncached.
EF Core companions / 30EF reservation quote companion
Eight independent BCL checks for proposed reservation arithmetic; no EF, SQL, transaction or storage emulation.
EF Core companions / 31EF read-scope and cursor companion
Eight independent BCL checks for supplied read scope, deletion policy and composite cursors; no authorization, EF translation or database emulation.
Runtime / 32Metadata-to-delegate routing lab
Discover a bounded set of annotated static methods, validate signatures, create real typed delegates, and run six console contract checks. No plugin loading or test framework is implied.
Runtime / 33Owned channel and lease contracts
Run six real bounded Channel and SemaphoreSlim ownership scenarios without OS threads, arbitrary sleeps, or invented worker behavior.
Production companions / 34Check full message equivalence and local effects
Run ten independent policy checks without pretending an in-memory owner is a durable inbox.
Production companions / 35Check conditional mutation and compatible receipts
Run twelve boundary checks for one-owner versions, identity reuse and current receipts.
Interview practice / 36Stock decision review harness
Twelve independent boundary and contract checks around pure checked stock decisions, without external storage.
Interview practice / 37Ranked keyset page contract
Fourteen checks for a deterministic composite order, bounded pages, continuation and invalid assumptions.
Memory / 38A bounded buffer lease report
Return pooled storage once while keeping only an independent report.
Memory / 39Checked admission memory budgets
Compare explicit payload owners and reject invalid capacity before arithmetic.