Different exit codes to indicate particular failures

src/coverlet.console/ExitCodes.cs

@@ -0,0 +1,34 @@
+using System;
+
+/// <summary>
+/// Exit Codes returned from Coverlet console process.
+/// </summary>
+[Flags]
+internal enum CommandExitCodes
+{
+    /// <summary>
+    /// Indicates successful run of dotnet test without any test failure and coverage percentage above threshold if provided.
+    /// </summary>
+    Success = 0,
+
+    /// <summary>
+    /// Indicates test failure by dotnet test.
+    /// </summary>
+    TestFailed = 1,
+
+    /// <summary>
+    /// Indicates coverage percentage is below given threshold for one or more threshold type.
+    /// </summary>
+    CoverageBelowThreshold = 2,
+
+    /// <summary>
+    /// Indicates exception occurred during Coverlet process.
+    /// </summary>
+    Exception = 101,
+
+    /// <summary>
+    /// Indicates missing options or empty arguments for Coverlet process.
+    /// </summary>
+    CommandParsingException = 102
+}
+

src/coverlet.console/Program.cs

@@ -23,6 +23,7 @@ static int Main(string[] args)
             app.FullName = "Cross platform .NET Core code coverage tool";
             app.HelpOption("-h|--help");
             app.VersionOption("-v|--version", GetAssemblyVersion());
+            int exitCode = (int)CommandExitCodes.Success;
 
             CommandArgument module = app.Argument("<ASSEMBLY>", "Path to the test assembly.");
             CommandOption target = app.Option("-t|--target", "Path to the test runner application.", CommandOptionType.SingleValue);
@@ -185,10 +186,14 @@ static int Main(string[] args)
                 coverageTable.AddRow("Average", $"{totalLinePercent / numModules}%", $"{totalBranchPercent / numModules}%", $"{totalMethodPercent / numModules}%");
 
                 logger.LogInformation(coverageTable.ToStringAlternative());
-
+                if (process.ExitCode > 0)
+                {
+                    exitCode += (int)CommandExitCodes.TestFailed;
+                }
                 thresholdTypeFlags = result.GetThresholdTypesBelowThreshold(summary, dThreshold, thresholdTypeFlags, dThresholdStat);
                 if (thresholdTypeFlags != ThresholdTypeFlags.None)
                 {
+                    exitCode += (int)CommandExitCodes.CoverageBelowThreshold;
                     var exceptionMessageBuilder = new StringBuilder();
                     if ((thresholdTypeFlags & ThresholdTypeFlags.Line) != ThresholdTypeFlags.None)
                     {
@@ -208,7 +213,7 @@ static int Main(string[] args)
                     throw new Exception(exceptionMessageBuilder.ToString());
                 }
 
-                return process.ExitCode == 0 ? 0 : process.ExitCode;
+                return exitCode;
             });
 
             try
@@ -219,12 +224,12 @@ static int Main(string[] args)
             {
                 logger.LogError(ex.Message);
                 app.ShowHelp();
-                return 1;
+                return (int)CommandExitCodes.CommandParsingException;
             }
             catch (Exception ex)
             {
                 logger.LogError(ex.Message);
-                return 1;
+                return exitCode > 0 ? exitCode : (int)CommandExitCodes.Exception;
             }
         }