S7 integration fixture — python-snap7 server closes the wire-level coverage gap (#216) + per-driver fixture coverage docs for every driver in the fleet. Closes #216. Two shipments in one PR because the docs landed as I surveyed each driver's fixture + the S7 work is the first wire-level-gap closer pulled from that survey.

S7 integration — AbCip/Modbus already have real-simulator integration suites; S7 had zero wire-level coverage despite being a Tier-A driver (all unit tests mocked IS7Client). Picked python-snap7's `snap7.server.Server` over raw Snap7 C library because `pip install` beats per-OS binary-pin maintenance, the package ships a Python __main__ shim that mirrors our existing pymodbus serve.ps1 + *.json pattern structurally, and the python-snap7 project is actively maintained. New project `tests/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/` with four moving parts: (a) `Snap7ServerFixture` — collection-scoped TCP probe on `localhost:1102` that sets `SkipReason` when the simulator's not running, matching the `ModbusSimulatorFixture` shape one directory over (same S7_SIM_ENDPOINT env var override convention for pointing at a real S7 CPU on port 102); (b) `PythonSnap7/` — `serve.ps1` wrapper + `server.py` shim + `s7_1500.json` seed profile + `README.md` documenting install / run / known limitations; (c) `S7_1500/S7_1500Profile.cs` — driver-side `S7DriverOptions` whose tag addresses map 1:1 to the JSON profile's seed offsets (DB1.DBW0 u16, DB1.DBW10 i16, DB1.DBD20 i32, DB1.DBD30 f32, DB1.DBX50.3 bool, DB1.DBW100 scratch); (d) `S7_1500SmokeTests` — three tests proving typed reads + write-then-read round-trip work through real S7netplus + real ISO-on-TCP + real snap7 server. Picked port 1102 default instead of S7-standard 102 because 102 is privileged on Linux + triggers Windows Firewall prompt; S7netplus 0.20 has a 5-arg `Plc(CpuType, host, port, rack, slot)` ctor that lets the driver honour `S7DriverOptions.Port`, but the existing driver code called the 4-arg overload + silently hardcoded 102. One-line driver fix (S7Driver.cs:87) threads `_options.Port` through — the S7 unit suite (58/58) still passes unchanged because every unit test uses a fake IS7Client that never sees the real ctor. Server seed-type matrix in `server.py` covers u8 / i8 / u16 / i16 / u32 / i32 / f32 / bool-with-bit / ascii (S7 STRING with max_len header). register_area takes the SrvArea enum value, not the string name — a 15-minute debug after the first test run caught that; documented inline.

Per-driver test-fixture coverage docs — eight new files in `docs/drivers/` laying out what each driver's harness actually benchmarks vs. what's trusted from field deployments. Pattern mirrors the AbServer-Test-Fixture.md doc that shipped earlier in this arc: TL;DR → What the fixture is → What it actually covers → What it does NOT cover → When-to-trust table → Follow-up candidates → Key files. Ugly truth the survey made visible: Galaxy + Modbus + (now) S7 + AB CIP have real wire-level coverage; AB Legacy / TwinCAT / FOCAS / OpcUaClient are still contract-only because their libraries ship no fake + no open-source simulator exists (AB Legacy PCCC), no public simulator exists (FOCAS), the vendor SDK has no in-process fake (TwinCAT/ADS.NET), or the test wiring just hasn't happened yet (OpcUaClient could trivially loopback against this repo's own server — flagged as #215). Each doc names the specific follow-up route: Snap7 server for S7 (done), TwinCAT 3 developer-runtime auto-restart for TwinCAT, Tier-C out-of-process Host for FOCAS, lab rigs for AB Legacy + hardware-gated bits of the others. `docs/drivers/README.md` gains a coverage-map section linking all eight. Tracking tasks #215-#222 filed for each PR-able follow-up.

Build clean (driver + integration project + docs); S7.Tests 58/58 (unchanged); S7.IntegrationTests 3/3 (new, verified end-to-end against a live python-snap7 server: `driver_reads_seeded_u16_through_real_S7comm`, `driver_reads_seeded_typed_batch`, `driver_write_then_read_round_trip_on_scratch_word`). Next fixture follow-up is #215 (OpcUaClient loopback against own server) — highest ROI of the remaining set, zero external deps.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/PythonSnap7/serve.ps1

@@ -0,0 +1,56 @@
+<#
+.SYNOPSIS
+    Launches the python-snap7 S7 server with one of the integration-test
+    profiles. Foreground process — Ctrl+C to stop. Mirrors the pymodbus
+    `serve.ps1` wrapper in tests\...\Modbus.IntegrationTests\Pymodbus\.
+
+.PARAMETER Profile
+    Which profile JSON to load: currently only 's7_1500' ships. Additional
+    families (S7-1200, S7-300) can drop in as new JSON files alongside.
+
+.PARAMETER Port
+    TCP port to bind. Default 1102 (non-privileged; matches
+    Snap7ServerFixture default endpoint). Pass 102 to match S7 standard —
+    requires root on Linux + triggers Windows Firewall prompt.
+
+.EXAMPLE
+    .\serve.ps1 -Profile s7_1500
+
+.EXAMPLE
+    .\serve.ps1 -Profile s7_1500 -Port 102
+#>
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory)] [ValidateSet('s7_1500')] [string]$Profile,
+    [int]$Port = 1102
+)
+
+$ErrorActionPreference = 'Stop'
+$here = $PSScriptRoot
+
+# python-snap7 installs the `snap7` Python package; we call via `python -m`
+# or via the server.py shim in this folder. Shim path is simpler to diagnose.
+$python = Get-Command python -ErrorAction SilentlyContinue
+if (-not $python) { $python = Get-Command py -ErrorAction SilentlyContinue }
+if (-not $python) {
+    Write-Error "python not found on PATH. Install Python 3.10+ and 'pip install python-snap7'."
+    exit 1
+}
+
+# Verify python-snap7 is installed so failures surface here, not in a
+# confusing ImportError from server.py.
+& $python.Source -c "import snap7.server" 2>$null
+if ($LASTEXITCODE -ne 0) {
+    Write-Error "python-snap7 not importable. Install with: pip install 'python-snap7>=2.0'"
+    exit 1
+}
+
+$jsonFile = Join-Path $here "$Profile.json"
+if (-not (Test-Path $jsonFile)) {
+    Write-Error "Profile config not found: $jsonFile"
+    exit 1
+}
+
+Write-Host "Starting python-snap7 server: profile=$Profile  TCP=localhost:$Port"
+Write-Host "Ctrl+C to stop."
+& $python.Source (Join-Path $here "server.py") $jsonFile --port $Port