Enforce .bicep file extension in build command

src/Bicep.Cli.IntegrationTests/BuildCommandTests.cs

@@ -1,6 +1,13 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using Bicep.Core;
 using Bicep.Core.Configuration;
 using Bicep.Core.FileSystem;
 using Bicep.Core.Registry;
@@ -15,12 +22,6 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 using Newtonsoft.Json.Linq;
-using System;
-using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
-using System.IO;
-using System.Linq;
-using System.Threading.Tasks;
 
 namespace Bicep.Cli.IntegrationTests
 {
@@ -45,6 +46,21 @@ public async Task Build_ZeroFiles_ShouldFail_WithExpectedErrorMessage()
             }
         }
 
+        [TestMethod]
+        public async Task Build_NonBicepFiles_ShouldFail_WithExpectedErrorMessage()
+        {
+            var (output, error, result) = await Bicep("build", "/dev/zero");
+
+            using (new AssertionScope())
+            {
+                result.Should().Be(1);
+                output.Should().BeEmpty();
+
+                error.Should().NotBeEmpty();
+                error.Should().Contain($@"The specified input ""/dev/zero"" was not recognized as a bicep file. Bicep files must use the {LanguageConstants.LanguageFileExtension} extension.");
+            }
+        }
+
         // TODO: handle variant linter messaging for each data test
         [DataTestMethod]
         [DynamicData(nameof(GetValidDataSets), DynamicDataSourceType.Method, DynamicDataDisplayNameDeclaringType = typeof(DataSet), DynamicDataDisplayName = nameof(DataSet.GetDisplayName))]
@@ -426,4 +442,3 @@ private static IEnumerable<object[]> GetValidDataSetsWithExternalModules() => Da
             .ToDynamicTestData();
     }
 }
-

src/Bicep.Cli/CliResources.resx

@@ -140,4 +140,8 @@ If you would like to report any issues or inaccurate conversions, please see htt
     <value>Unrecognized arguments "{0}" specified. Use "{1} --help" to view available options.</value>
     <comment>{0} arguments    {1} exe name</comment>
   </data>
+  <data name="UnrecognizedFileExtensionMessage" xml:space="preserve">
+    <value>The specified input "{0}" was not recognized as a bicep file. Bicep files must use the .bicep extension.</value>
+    <comment>{0} input file path</comment>
+  </data>
 </root>

src/Bicep.Cli/Commands/BuildCommand.cs

@@ -1,12 +1,12 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System.Threading.Tasks;
 using Bicep.Cli.Arguments;
 using Bicep.Cli.Logging;
 using Bicep.Cli.Services;
 using Bicep.Core.FileSystem;
 using Microsoft.Extensions.Logging;
-using System.Threading.Tasks;
 
 namespace Bicep.Cli.Commands
 {
@@ -46,6 +46,12 @@ public async Task<int> RunAsync(BuildArguments args)
                 logger.LogWarning(CliResources.ResourceTypesDisclaimerMessage);
             }
 
+            if (!IsBicepFile(inputPath))
+            {
+                logger.LogError(CliResources.UnrecognizedFileExtensionMessage, inputPath);
+                return 1;
+            }
+
             var compilation = await compilationService.CompileAsync(inputPath, args.NoRestore);
 
             if (diagnosticLogger.ErrorCount < 1)
@@ -67,5 +73,7 @@ public async Task<int> RunAsync(BuildArguments args)
             // return non-zero exit code on errors
             return diagnosticLogger.ErrorCount > 0 ? 1 : 0;
         }
+
+        private bool IsBicepFile(string inputPath) => PathHelper.HasBicepExtension(PathHelper.FilePathToFileUrl(inputPath));
     }
 }