Fix OverflowException when estimating the progress remaining time (#404)

Fix OverflowException when estimating the progress remaining time

src/Spectre.Console.Tests/Unit/Progress/ProgressTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Threading.Tasks;
 using Shouldly;
 using Spectre.Console.Testing;
@@ -241,5 +242,30 @@ namespace Spectre.Console.Tests.Unit
                     "          \n" + // bottom padding
                     "[?25h"); // show cursor
         }
+
+        [Fact]
+        public void Should_Report_Max_Remaining_Time_For_Extremely_Small_Progress()
+        {
+            // Given
+            var console = new TestConsole()
+                .Interactive();
+
+            var task = default(ProgressTask);
+            var progress = new Progress(console)
+                .Columns(new[] { new RemainingTimeColumn() })
+                .AutoRefresh(false)
+                .AutoClear(false);
+
+            // When
+            progress.Start(ctx =>
+            {
+                task = ctx.AddTask("foo");
+                task.Increment(double.Epsilon);
+                task.Increment(double.Epsilon);
+            });
+
+            // Then
+            task.RemainingTime.ShouldBe(TimeSpan.MaxValue);
+        }
     }
 }

src/Spectre.Console/Widgets/Progress/ProgressTask.cs

@@ -286,20 +286,20 @@ namespace Spectre.Console
                 }
 
                 var speed = GetSpeed();
-                if (speed == null)
+                if (speed == null || speed == 0)
                 {
                     return null;
                 }
 
-                // If the speed is zero, the estimate below
+                // If the speed is near zero, the estimate below causes the
-                // will return infinity (since it's a double),
+                // TimeSpan creation to throw an OverflowException. Just return
-                // so let's set the speed to 1 in that case.
+                // the maximum possible remaining time instead of overflowing.
-                if (speed == 0)
+                var estimate = (MaxValue - Value) / speed.Value;
+                if (estimate > TimeSpan.MaxValue.TotalSeconds)
                 {
-                    speed = 1;
+                    return TimeSpan.MaxValue;
                 }
 
-                var estimate = (MaxValue - Value) / speed.Value;
                 return TimeSpan.FromSeconds(estimate);
             }
         }