# TeslaConsole.DiffTests — differential equivalence suite

Verifies that the **reconstructed** `TeslaConsole.exe` (built from the decompiled
source in this repo) behaves identically to the **original** reference binary in
[`original/TeslaConsole.exe`](../../original/TeslaConsole.exe).

## How it works

The suite loads each assembly into its **own child AppDomain**
(`DifferentialFixture`) and drives it through a `MarshalByRefObject` proxy
(`Invoker`). This is why the project targets **net48** — AppDomains are a .NET
Framework feature. The **original** is the `4.11.3.37076` baseline; the **recovered**
build is the modernized `4.11.4.x` line (same `TeslaConsole` assembly name, an
intentionally newer version). Because the two versions differ, the public-member
comparison strips `Version=` stamps before diffing — it compares type/member *names*,
not assembly versions.

Each child domain is given a probe directory (the recovered build's output, which
ships every dependency DLL) so the original — which is distributed without its
proprietary dependencies — still resolves its references for metadata inspection.

### What is compared

1. **Public API surface** (`PublicApiSurfaceTests`)
   Every public type and public member (signature-for-signature) exposed by the
   original must also be exposed by the recovered build. Compiler-generated members
   and property/event accessor methods are excluded — the README at the repo root
   notes those legitimately differ between a decompilation and the lost sources.

2. **Recovered-only characterization** (`CatalogTests`, `BTGoldenEggTests`)
   Features that were *added* in the reconstruction have no counterpart in the
   original exe, so these run against the recovered build only:
   - `CatalogTests` — the data-driven product catalog reproduces the exact
     `LaunchData` the old hardcoded code emitted.
   - `BTGoldenEggTests` — the new `TeslaConsole.BattleTech` mission builder is
     diffed field-by-field against two golden eggs captured from the original
     consoles ([`BattleTech/cavern.egg`](BattleTech/cavern.egg),
     [`BattleTech/TESTARN.EGG`](BattleTech/TESTARN.EGG)). The comparison is
     per-section and order-independent (the pod parses eggs INI-style; the two
     golden eggs themselves disagree on field order). Font-rendered name-bitmap
     pixel rows are excluded, but TESTARN's ordinal art — identical to the
     RP-inherited rows — is compared byte-exactly. Also covers the
     `EggFileMessage` wire framing (NUL-delimited ASCII, 1000-byte chunks,
     byte-exact reassembly), role-block de-duplication, the No Return mode
     (same `scenario=freeforall`, different role), and the shipped
     `BattleTech\BTConfig.xml` catalog contents.

3. **Behavioral output** (`BehavioralEquivalenceTests`)
   The same deterministic, dependency-free methods are invoked in *both* assemblies
   over a battery of inputs and the results must match byte-for-byte:
   - `RPStrings.GetTimeString` (mm:ss formatting + 0.5 s rounding)
   - `HostTypeHelper.Parse(...).ToString()` (incl. invalid-input exceptions)
   - `PlasmaBitmaps.ConvertBitmap` (1-bpp packing of a known pixel pattern)
   - `PlasmaBitmaps.GenerateString` (full GDI text → 1-bpp plasma pipeline)
   - `RPMap` / `RPVehicle` XML parsing
   - `SiteManagement` well-known application GUID constants
   - `Tuple.Create<,>` generic factory

   A negative-control test (`Harness_Distinguishes_Different_Outputs`) proves the
   harness can actually see a difference, so a green run is never vacuous.

The project also carries two **byte-compatibility guards** — not original-vs-recovered
comparisons, but checks that the modernized protocol/crypto stays compatible with the
original binaries:

- `PodRpcProtocolTests` — round-trips the framed-JSON RPC ([`Contract/PodRpcProtocol.cs`](../../../Contract/PodRpcProtocol.cs))
  in-process: every request/response shape encodes and decodes back to the same values.
- `SecureConfigCompatTests` — asserts the source-built `OFBCryptoStream` produces
  byte-identical ciphertext to the original `TeslaSecureConfiguration.dll`, so the pod
  provisioning handshake stays wire-compatible.

## Running

```
dotnet test tests/TeslaConsole.DiffTests/TeslaConsole.DiffTests.csproj
```

A project reference builds the reconstruction first, and the suite always tests
the most recently built `bin/{Debug,Release}/net48/TeslaConsole.exe`.

## Scope / limitations

This compares **deterministic logic**. It deliberately does not drive the WinForms
UI, the pod networking, secure-configuration, or hardware-facing code — those
require the live console, its pods, and the proprietary services, and are not
reproducible in a unit test. The API-surface test still asserts those types exist
with matching signatures even though their behavior isn't exercised.