Joseph Doherty
97 lines
4.1 KiB
C#
97 lines
4.1 KiB
C#
using Shouldly;
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using Xunit;
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namespace ZB.MOM.WW.OtOpcUa.Driver.S7.Tests;
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/// <summary>
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/// Config-time guard on the two span-read knobs. There is no <c>IValidateOptions</c> machinery
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/// for S7 — <see cref="S7DriverFactoryExtensions.ParseOptions"/> is the single choke point every
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/// deployed config passes through — so a nonsensical value used to be accepted at deploy time and
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/// only misbehave later, in the read loop, on a driver that had already reported healthy.
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/// </summary>
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/// <remarks>
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/// The legal-value cases matter as much as the rejections: <c>-1</c> on the gap is the documented
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/// escape hatch that disables grouping entirely (<c>S7Driver</c> enables spans on <c>>= 0</c>),
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/// and <c>0</c> means "tolerate no gap at all", i.e. merge only strictly adjacent tags. A guard
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/// written as <c>< 0</c> would break both.
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/// </remarks>
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public sealed class S7SpanOptionValidationTests
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{
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/// <summary>A driver-config blob carrying the given span knob, host included (it is required).</summary>
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private static string Config(string knob, int value) =>
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"{\"host\":\"10.0.0.1\",\"" + knob + "\":" + value.ToString(System.Globalization.CultureInfo.InvariantCulture) + "}";
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/// <summary>A span cap below one can never admit a single planned block read, so it is rejected.</summary>
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[Theory]
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[InlineData(0)]
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[InlineData(-1)]
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[InlineData(-220)]
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public void A_span_cap_below_one_is_rejected(int maxSpanBytes)
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{
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var ex = Should.Throw<InvalidOperationException>(() => S7DriverFactoryExtensions.ParseOptions(
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"s7-cfg", Config("spanReadMaxSpanBytes", maxSpanBytes)));
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ex.Message.ShouldContain("SpanReadMaxSpanBytes");
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ex.Message.ShouldContain("s7-cfg");
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}
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/// <summary>A gap budget below the grouping-disabled sentinel is rejected.</summary>
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[Theory]
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[InlineData(-2)]
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[InlineData(-16)]
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public void A_gap_budget_below_minus_one_is_rejected(int maxGapBytes)
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{
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var ex = Should.Throw<InvalidOperationException>(() => S7DriverFactoryExtensions.ParseOptions(
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"s7-cfg", Config("spanReadMaxGapBytes", maxGapBytes)));
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ex.Message.ShouldContain("SpanReadMaxGapBytes");
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ex.Message.ShouldContain("s7-cfg");
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}
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/// <summary>
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/// The two legal edge values survive: <c>-1</c> (grouping disabled) and <c>0</c> (no gap
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/// tolerated). Both are documented behaviour, not degenerate input.
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/// </summary>
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[Theory]
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[InlineData(-1)]
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[InlineData(0)]
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public void The_documented_gap_edge_values_are_accepted(int maxGapBytes)
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{
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var parsed = S7DriverFactoryExtensions.ParseOptions("s7-cfg", Config("spanReadMaxGapBytes", maxGapBytes));
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parsed.SpanReadMaxGapBytes.ShouldBe(maxGapBytes);
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}
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/// <summary>A one-byte span cap is the smallest legal cap and must not trip the guard.</summary>
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[Fact]
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public void The_smallest_legal_span_cap_is_accepted()
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{
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var parsed = S7DriverFactoryExtensions.ParseOptions("s7-cfg", Config("spanReadMaxSpanBytes", 1));
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parsed.SpanReadMaxSpanBytes.ShouldBe(1);
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}
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/// <summary>
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/// An over-PDU span cap is legal — S7.Net transparently chunks an oversized <c>ReadBytes</c>
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/// into several wire requests — so the guard must not invent an upper bound it cannot know
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/// (the negotiated PDU size is opaque inside S7.Net).
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/// </summary>
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[Fact]
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public void An_over_pdu_span_cap_is_accepted_because_S7Net_chunks_it()
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{
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var parsed = S7DriverFactoryExtensions.ParseOptions("s7-cfg", Config("spanReadMaxSpanBytes", 4096));
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parsed.SpanReadMaxSpanBytes.ShouldBe(4096);
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}
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/// <summary>Omitting both knobs keeps the shipped defaults, which must themselves pass the guard.</summary>
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[Fact]
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public void The_shipped_defaults_pass_the_guard()
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{
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var parsed = S7DriverFactoryExtensions.ParseOptions("s7-cfg", "{\"host\":\"10.0.0.1\"}");
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parsed.SpanReadMaxGapBytes.ShouldBe(S7DriverOptions.DefaultSpanReadMaxGapBytes);
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parsed.SpanReadMaxSpanBytes.ShouldBe(S7DriverOptions.DefaultSpanReadMaxSpanBytes);
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}
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}
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