Improve error message when project file does not exist.

Resolve #171

src/Microsoft.Extensions.SecretManager.Tools/Program.cs

@@ -151,6 +151,11 @@ namespace Microsoft.Extensions.SecretManager.Tools
 
             var fileInfo = new PhysicalFileInfo(new FileInfo(projectPath));
 
+            if (!fileInfo.Exists)
+            {
+                throw new GracefulException(Resources.FormatError_ProjectPath_NotFound(projectPath));
+            }
+
             Logger.LogDebug(Resources.Message_Project_File_Path, fileInfo.PhysicalPath);
             return ReadUserSecretsId(fileInfo);
         }

src/Microsoft.Extensions.SecretManager.Tools/Properties/Resources.Designer.cs

@@ -58,6 +58,22 @@ namespace Microsoft.Extensions.SecretManager.Tools
             return GetString("Error_No_Secrets_Found");
         }
 
+        /// <summary>
+        /// The project file '{path}' does not exist.
+        /// </summary>
+        internal static string Error_ProjectPath_NotFound
+        {
+            get { return GetString("Error_ProjectPath_NotFound"); }
+        }
+
+        /// <summary>
+        /// The project file '{path}' does not exist.
+        /// </summary>
+        internal static string FormatError_ProjectPath_NotFound(object path)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("Error_ProjectPath_NotFound", "path"), path);
+        }
+
         /// <summary>
         /// Project file path {project}.
         /// </summary>

src/Microsoft.Extensions.SecretManager.Tools/Resources.resx

@@ -126,6 +126,9 @@
   <data name="Error_No_Secrets_Found" xml:space="preserve">
     <value>No secrets configured for this application.</value>
   </data>
+  <data name="Error_ProjectPath_NotFound" xml:space="preserve">
+    <value>The project file '{path}' does not exist.</value>
+  </data>
   <data name="Message_Project_File_Path" xml:space="preserve">
     <value>Project file path {project}.</value>
   </data>

test/Microsoft.Extensions.SecretManager.Tools.Tests/SecretManagerTests.cs

@@ -10,6 +10,7 @@ using Microsoft.Extensions.Configuration.UserSecrets.Tests;
 using Microsoft.Extensions.Logging;
 using Xunit;
 using Xunit.Abstractions;
+using Microsoft.Extensions.SecretManager.Tools.Internal;
 
 namespace Microsoft.Extensions.SecretManager.Tools.Tests
 {
@@ -22,6 +23,17 @@ namespace Microsoft.Extensions.SecretManager.Tools.Tests
             _logger = new TestLogger(output);
         }
 
+        [Fact]
+        public void Error_Project_DoesNotExist()
+        {
+            var projectPath = Path.Combine(Path.GetTempPath(), "dne", Guid.NewGuid().ToString(), "project.json");
+            var secretManager = new Program(Console.Out, Directory.GetCurrentDirectory()) { Logger = _logger };
+
+            var ex = Assert.Throws<GracefulException>(() => secretManager.RunInternal("list", "--project", projectPath));
+
+            Assert.Equal(ex.Message, Resources.FormatError_ProjectPath_NotFound(projectPath));
+        }
+
         [Theory]
         [InlineData(true)]
         [InlineData(false)]