dotnet tool install --local works by default, by creating a manifest by default, utilizing --create-manifest-if-needed

src/Cli/dotnet/Commands/Tool/Install/ToolInstallCommandParser.cs

@@ -51,7 +51,8 @@ internal static class ToolInstallCommandParser
     public static readonly Option<bool> CreateManifestIfNeededOption = new("--create-manifest-if-needed")
     {
         Description = CliCommandStrings.CreateManifestIfNeededOptionDescription,
-        Arity = ArgumentArity.Zero
+        Arity = ArgumentArity.ZeroOrOne,
+        DefaultValueFactory = _ => true,
     };
 
     public static readonly Option<bool> AllowPackageDowngradeOption = new("--allow-downgrade")

test/dotnet.Tests/CommandTests/Tool/Install/ToolInstallLocalCommandTests.cs

@@ -128,22 +128,41 @@ public void WhenRunWithPackageIdItShouldSaveToCacheAndAddToManifestFile()
         }
 
         [Fact]
-        public void GivenNoManifestFileItShouldThrow()
+        public void GivenCreateManifestIfNeededWithoutArgumentTheDefaultIsTrueForLegacyBehavior()
         {
             _fileSystem.File.Delete(_manifestFilePath);
-            var toolInstallLocalCommand = GetDefaultTestToolInstallLocalCommand();
+            ParseResult parseResult =
+            Parser.Instance.Parse(
+               $"dotnet tool install {_packageIdA.ToString()} --create-manifest-if-needed");
 
-            Action a = () => toolInstallLocalCommand.Execute();
-            a.Should().Throw<GracefulException>()
-                .And.Message.Should()
-                .Contain(CliStrings.CannotFindAManifestFile);
+            var toolInstallLocalCommand = new ToolInstallLocalCommand(
+                parseResult,
+                _packageIdA,
+                _toolPackageDownloaderMock,
+                _toolManifestFinder,
+                _toolManifestEditor,
+                _localToolsResolverCache,
+                _reporter);
+
+            toolInstallLocalCommand.Execute().Should().Be(0);
         }
 
         [Fact]
         public void GivenNoManifestFileItShouldThrowAndContainNoManifestGuide()
         {
             _fileSystem.File.Delete(_manifestFilePath);
-            var toolInstallLocalCommand = GetDefaultTestToolInstallLocalCommand();
+            ParseResult parseResult =
+            Parser.Instance.Parse(
+               $"dotnet tool install {_packageIdA.ToString()} --create-manifest-if-needed false");
+
+            var toolInstallLocalCommand = new ToolInstallLocalCommand(
+                parseResult,
+                _packageIdA,
+                _toolPackageDownloaderMock,
+                _toolManifestFinder,
+                _toolManifestEditor,
+                _localToolsResolverCache,
+                _reporter);
 
             Action a = () => toolInstallLocalCommand.Execute();
             a.Should().Throw<GracefulException>()
@@ -408,6 +427,28 @@ public void GivenNoManifestFileAndCreateManifestIfNeededFlagItShouldCreateManife
             _fileSystem.File.Exists(Path.Combine(_temporaryDirectory, ".config", "dotnet-tools.json")).Should().BeTrue();
         }
 
+        [Fact]
+        public void GivenNoManifestFileItUsesCreateManifestIfNeededByDefault()
+        {
+            _fileSystem.File.Delete(_manifestFilePath);
+
+            ParseResult parseResult =
+                Parser.Instance.Parse(
+                    $"dotnet tool install {_packageIdA.ToString()}");
+
+            var installLocalCommand = new ToolInstallLocalCommand(
+                parseResult,
+                _packageIdA,
+                _toolPackageDownloaderMock,
+                _toolManifestFinder,
+                _toolManifestEditor,
+                _localToolsResolverCache,
+                _reporter);
+
+            installLocalCommand.Execute().Should().Be(0);
+            _fileSystem.File.Exists(Path.Combine(_temporaryDirectory, ".config", "dotnet-tools.json")).Should().BeTrue();
+        }
+
         [Fact]
         public void GivenNoManifestFileAndCreateManifestIfNeededFlagItShouldCreateManifestInSln()
         {