Joseph Doherty
56 lines
2.3 KiB
C#
56 lines
2.3 KiB
C#
using ZB.MOM.WW.ScadaBridge.Commons.Entities.ExternalSystems;
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namespace ZB.MOM.WW.ScadaBridge.ExternalSystemGateway.Tests;
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/// <summary>Tests for <see cref="ExternalDefinitionLookupCache"/> (review 2026-10-21 05/P2).</summary>
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public class ExternalDefinitionLookupCacheTests
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{
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private static ExternalSystemDefinition Sys() => new("S", "https://x", "none") { Id = 1 };
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/// <summary>Verifies hits within the TTL skip the repository and expiry refetches.</summary>
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/// <returns>A task that represents the asynchronous operation.</returns>
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[Fact]
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public async Task Hit_WithinTtl_SkipsFetch_AndExpiryRefetches()
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{
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var time = new FakeTimeProvider(DateTimeOffset.UtcNow);
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var cache = new ExternalDefinitionLookupCache(TimeSpan.FromSeconds(5), time);
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var fetches = 0;
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Task<ExternalSystemDefinition?> Fetch() { fetches++; return Task.FromResult<ExternalSystemDefinition?>(Sys()); }
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await cache.GetSystemAsync("S", Fetch);
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await cache.GetSystemAsync("S", Fetch);
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Assert.Equal(1, fetches);
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time.Advance(TimeSpan.FromSeconds(6));
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await cache.GetSystemAsync("S", Fetch);
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Assert.Equal(2, fetches);
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}
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/// <summary>Verifies misses are not cached and a zero TTL disables caching.</summary>
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/// <returns>A task that represents the asynchronous operation.</returns>
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[Fact]
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public async Task NotFound_IsNotCached_AndZeroTtlDisables()
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{
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var cache = new ExternalDefinitionLookupCache(TimeSpan.FromSeconds(5));
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var fetches = 0;
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Task<ExternalSystemDefinition?> Miss() { fetches++; return Task.FromResult<ExternalSystemDefinition?>(null); }
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await cache.GetSystemAsync("S", Miss);
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await cache.GetSystemAsync("S", Miss);
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Assert.Equal(2, fetches);
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var off = new ExternalDefinitionLookupCache(TimeSpan.Zero);
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fetches = 0;
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Task<ExternalSystemDefinition?> Hit() { fetches++; return Task.FromResult<ExternalSystemDefinition?>(Sys()); }
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await off.GetSystemAsync("S", Hit);
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await off.GetSystemAsync("S", Hit);
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Assert.Equal(2, fetches);
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}
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private sealed class FakeTimeProvider(DateTimeOffset start) : TimeProvider
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{
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private DateTimeOffset _now = start;
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public override DateTimeOffset GetUtcNow() => _now;
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public void Advance(TimeSpan by) => _now += by;
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}
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}
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