Override ProcessOutputLine.ToString() to return Content

src/libraries/System.Diagnostics.Process/ref/System.Diagnostics.Process.cs

@@ -285,6 +285,7 @@ public readonly partial struct ProcessOutputLine
         public ProcessOutputLine(string content, bool standardError) { throw null; }
         public string Content { get { throw null; } }
         public bool StandardError { get { throw null; } }
+        public override string ToString() { throw null; }
     }
     public enum ProcessPriorityClass
     {

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/ProcessOutputLine.cs

@@ -35,5 +35,11 @@ public ProcessOutputLine(string content, bool standardError)
         /// otherwise, <see langword="false" />.
         /// </value>
         public bool StandardError { get; }
+
+        /// <summary>
+        /// Returns the text content of the output line, or <see cref="string.Empty"/> if the struct was default-initialized.
+        /// </summary>
+        /// <returns>The value of <see cref="Content"/>, or <see cref="string.Empty"/> if <see cref="Content"/> is <see langword="null"/>.</returns>
+        public override string ToString() => Content ?? string.Empty;
     }
 }

src/libraries/System.Diagnostics.Process/tests/ProcessStreamingTests.cs

@@ -694,5 +694,25 @@ private Process StartLinePrintingProcess(string stdOutText, string stdErrText)
 
             return (capturedOutput, capturedError);
         }
+
+        [Theory]
+        [InlineData("hello")]
+        [InlineData("")]
+        [InlineData("line with spaces")]
+        public void ProcessOutputLine_ToString_ReturnsContent(string content)
+        {
+            ProcessOutputLine line = new(content, standardError: false);
+            Assert.Equal(content, line.ToString());
+
+            ProcessOutputLine errorLine = new(content, standardError: true);
+            Assert.Equal(content, errorLine.ToString());
+        }
+
+        [Fact]
+        public void ProcessOutputLine_Default_ToString_ReturnsEmpty()
+        {
+            ProcessOutputLine line = default;
+            Assert.Equal(string.Empty, line.ToString());
+        }
     }
 }