Use single dash for single letter command line options in QIR driver generator (#820)

* Use single dash for single letter command line options

* Use property

* Rename Argument to ToArgument

src/Qir/Tests/Tools/QirDriverGeneratorTests.cs

@@ -180,5 +180,56 @@ namespace Tests.Microsoft.Quantum.Qir.Runtime.Tools
             Assert.Equal(verificationCppSourceCode, generatedCppSourceCode);
             generatedStream.Close();
         }
+
+        [Theory]
+        [MemberData(nameof(CommandLineArgumentsData))]
+        public void GenerateCommandLineArguments(string expected, ExecutionInformation info)
+        {
+            var generator = new QirFullStateDriverGenerator(false);
+            Assert.Equal(expected, generator.GetCommandLineArguments(info));
+        }
+
+        public static IEnumerable<object[]> CommandLineArgumentsData
+        {
+            get
+            {
+                static object[] TestCase(
+                    string expected, List<Parameter> parameters, Dictionary<string, ArgumentValue> arguments) =>
+                    new object[]
+                    {
+                        expected,
+                        new ExecutionInformation
+                        {
+                            EntryPoint = new EntryPointOperation { Parameters = parameters },
+                            ArgumentValues = arguments
+                        }
+                    };
+
+                yield return TestCase(
+                    "--foo 5",
+                    new List<Parameter> { new Parameter { Name = "foo", Position = 0, Type = DataType.IntegerType } },
+                    new Dictionary<string, ArgumentValue>
+                        { ["foo"] = new ArgumentValue { Type = DataType.IntegerType, Integer = 5 } });
+
+                yield return TestCase(
+                    "-n 5",
+                    new List<Parameter> { new Parameter { Name = "n", Position = 0, Type = DataType.IntegerType } },
+                    new Dictionary<string, ArgumentValue>
+                        { ["n"] = new ArgumentValue { Type = DataType.IntegerType, Integer = 5 } });
+
+                yield return TestCase(
+                    "--foo 5 --bar \"abc\"",
+                    new List<Parameter>
+                    {
+                        new Parameter { Name = "bar", Position = 1, Type = DataType.StringType },
+                        new Parameter { Name = "foo", Position = 0, Type = DataType.IntegerType }
+                    },
+                    new Dictionary<string, ArgumentValue>
+                    {
+                        ["bar"] = new ArgumentValue { Type = DataType.StringType, String = "abc" },
+                        ["foo"] = new ArgumentValue { Type = DataType.IntegerType, Integer = 5 }
+                    });
+            }
+        }
     }
 }

src/Qir/Tools/Driver/QirCppDriverGenerator.cs

@@ -33,20 +33,15 @@ namespace Microsoft.Quantum.Qir.Runtime.Tools.Driver
 
         public string GetCommandLineArguments(ExecutionInformation executionInformation)
         {
-            // Sort arguments by position.
-            var sortedArguments = executionInformation.EntryPoint.Parameters.OrderBy(arg => arg.Position);
-            var argumentBuilder = new StringBuilder();
-            foreach (var arg in sortedArguments)
+            string ToArgument(Parameter param)
             {
-                if (argumentBuilder.Length != 0)
-                {
-                    argumentBuilder.Append(' ');
-                }
-
-                argumentBuilder.Append($"--{arg.Name}").Append(' ').Append(GetArgumentValueString(arg, executionInformation.ArgumentValues[arg.Name]));
+                var prefix = param.Name.Length > 1 ? "--" : "-";
+                var value = GetArgumentValueString(param, executionInformation.ArgumentValues[param.Name]);
+                return $"{prefix}{param.Name} {value}";
             }
 
-            return argumentBuilder.ToString();
+            var parameters = executionInformation.EntryPoint.Parameters.OrderBy(param => param.Position);
+            return string.Join(" ", parameters.Select(ToArgument));
         }
 
         private static string GetArgumentValueString(Parameter argument, ArgumentValue argumentValue)