[ci skip] docs: add comment explaining my absolute pain

X10D.Tests/src/IO/TextWriterTests.cs

@@ -15,6 +15,17 @@ public partial class TextWriterTests
     {
         _stream = new MemoryStream();
         _writer = new StreamWriter(_stream, Encoding.UTF8);
+
+        // When StreamWriter flushes for the first time, an encoding preamble is written to the stream,
+        // which is correctly mirrored by the behaviour of StreamReader.
+        // however, we're not using StreamReader, we read the contents of the stream
+        // using MemoryStream.ToArray(). This was causing one test to fail, as the first test
+        // that runs would cause the preamble to be written and not be accounted for when reading.
+        // Subsequent tests would pass since the preamble would not be written again.
+        // The following 4 lines ensure that the preamble is written by manually flushing the
+        // writer after writing a single space character. We then clear the stream, and allow
+        // unit tests to do their thing. This took me an HOUR AND A HALF to narrow down.
+        // I want to fucking die.
         _writer.Write(' ');
         _writer.Flush();
         _stream.SetLength(0);