test(worker): deterministic pump-wait ordering, env hermeticity, ResolveWriteCompletionTimeout coverage

src/ZB.MOM.WW.MxGateway.Worker.Tests/MxAccess/MxAccessStaSessionTests.cs

@@ -15,6 +15,48 @@ namespace ZB.MOM.WW.MxGateway.Worker.Tests.MxAccess;
 /// </summary>
 public sealed class MxAccessStaSessionTests
 {
+    /// <summary>
+    ///     Verifies the launcher-env-var parse branches of
+    ///     <see cref="MxAccessStaSession.ResolveWriteCompletionTimeout"/>:
+    ///     a valid non-negative value is honored (0 = disabled), while a
+    ///     missing, malformed, or negative value falls back to the executor
+    ///     default. Env mutation is restored in a finally so parallel tests
+    ///     never observe the temporary value.
+    /// </summary>
+    /// <param name="rawValue">Raw env-var value, or null for unset.</param>
+    /// <param name="expectedMilliseconds">Expected resolved wait, or null for the executor default.</param>
+    [Theory]
+    [InlineData(null, null)]
+    [InlineData("", null)]
+    [InlineData("junk", null)]
+    [InlineData("-5", null)]
+    [InlineData("0", 0)]
+    [InlineData("250", 250)]
+    public void ResolveWriteCompletionTimeout_ParsesEnvironmentValue(string? rawValue, int? expectedMilliseconds)
+    {
+        string? original = Environment.GetEnvironmentVariable(
+            MxAccessStaSession.WriteCompletionWaitEnvironmentVariableName);
+        try
+        {
+            Environment.SetEnvironmentVariable(
+                MxAccessStaSession.WriteCompletionWaitEnvironmentVariableName,
+                rawValue);
+
+            TimeSpan resolved = MxAccessStaSession.ResolveWriteCompletionTimeout();
+
+            TimeSpan expected = expectedMilliseconds is null
+                ? MxAccessCommandExecutor.DefaultWriteCompletionTimeout
+                : TimeSpan.FromMilliseconds(expectedMilliseconds.Value);
+            Assert.Equal(expected, resolved);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable(
+                MxAccessStaSession.WriteCompletionWaitEnvironmentVariableName,
+                original);
+        }
+    }
+
     /// <summary>
     /// Verifies that StartAsync creates the MXAccess COM object and attaches the event sink on the STA thread.
     /// </summary>