Fix #157: Tests using OutputReader sometimes hang

This fix handles an edge case when buffered output that ends with a
newline is treated incorrectly causing an extra empty line to be returend
by the OutputReader.

Author: daviwil

test/PowerShellEditorServices.Test.Host/LanguageServerTests.cs

@@ -490,8 +490,8 @@ await requestContext.SendResult(
                     ChosenItem = "a"
                 });
 
-            // Skip the initial script lines (6 script lines plus 3 blank lines)
-            await outputReader.ReadLines(9);
+            // Skip the initial script lines (6 script lines plus 2 blank lines)
+            string[] outputLines = await outputReader.ReadLines(8);
 
             // Wait for the selection to appear as output
             await evaluateTask;

test/PowerShellEditorServices.Test.Host/OutputReader.cs

@@ -89,9 +89,11 @@ public async Task<string> ReadLine(string expectedOutputCategory = "stdout")
                                     outputLines[i],
 
                                     // The line has a newline if it's not the last segment or
-                                    // if the current output string ends with a newline
+                                    // if the last segment is not an empty string and the
+                                    // complete output string ends with a newline
                                     i < outputLines.Length - 1 ||
-                                    nextOutputEvent.Output.EndsWith("\n")));
+                                    (outputLines[outputLines.Length - 1].Length > 0 &&
+                                     nextOutputEvent.Output.EndsWith("\n"))));
                         }
                     }