.NET: Add unit tests for declarative executor SetMultipleVariables (microsoft#2016)

* Add unit tests for create conversation executor

* Update indentation and comment typo.

* Added unit tests for declarative executor SetMultipleVariablesExecutor

* Updated comments and syntactic sugar

Author: peibekwe

dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/SetMultipleVariablesExecutorTest.cs

@@ -0,0 +1,154 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Threading.Tasks;
+using Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
+using Microsoft.Bot.ObjectModel;
+using Microsoft.PowerFx.Types;
+using Xunit.Abstractions;
+
+namespace Microsoft.Agents.AI.Workflows.Declarative.UnitTests.ObjectModel;
+
+/// <summary>
+/// Tests for <see cref="SetMultipleVariablesExecutor"/>.
+/// </summary>
+public sealed class SetMultipleVariablesExecutorTest(ITestOutputHelper output) : WorkflowActionExecutorTest(output)
+{
+    [Fact]
+    public async Task SetMultipleVariablesAsync()
+    {
+        // Arrange, Act, Assert
+        await this.ExecuteTestAsync(
+            displayName: nameof(SetMultipleVariablesAsync),
+            assignments: [
+                new AssignmentCase("Variable1", new NumberDataValue(42), FormulaValue.New(42)),
+                new AssignmentCase("Variable2", new StringDataValue("Test"), FormulaValue.New("Test")),
+                new AssignmentCase("Variable3", new BooleanDataValue(true), FormulaValue.New(true))
+            ]);
+    }
+
+    [Fact]
+    public async Task SetMultipleVariablesWithExpressionsAsync()
+    {
+        // Arrange
+        this.State.Set("SourceNumber", FormulaValue.New(10));
+        this.State.Set("SourceText", FormulaValue.New("Hello"));
+        this.State.Bind();
+
+        // Act, Assert
+        await this.ExecuteTestAsync(
+            displayName: nameof(SetMultipleVariablesWithExpressionsAsync),
+            assignments: [
+                new AssignmentCase("CalcVariable", ValueExpression.Expression("Local.SourceNumber * 2"), FormulaValue.New(20)),
+                new AssignmentCase("ConcatVariable", ValueExpression.Expression(@"Concatenate(Local.SourceText, "" World"")"), FormulaValue.New("Hello World")),
+                new AssignmentCase("BoolVariable", ValueExpression.Expression("Local.SourceNumber > 5"), FormulaValue.New(true))
+            ]);
+    }
+
+    [Fact]
+    public async Task SetMultipleVariablesWithVariableReferencesAsync()
+    {
+        // Arrange
+        this.State.Set("Source1", FormulaValue.New(123));
+        this.State.Set("Source2", FormulaValue.New("Reference"));
+        this.State.Bind();
+
+        // Act, Assert
+        await this.ExecuteTestAsync(
+            displayName: nameof(SetMultipleVariablesWithVariableReferencesAsync),
+            assignments: [
+                new AssignmentCase("Target1", ValueExpression.Variable(PropertyPath.TopicVariable("Source1")), FormulaValue.New(123)),
+                new AssignmentCase("Target2", ValueExpression.Variable(PropertyPath.TopicVariable("Source2")), FormulaValue.New("Reference"))
+            ]);
+    }
+
+    [Fact]
+    public async Task SetMultipleVariablesWithNullValuesAsync()
+    {
+        // Arrange, Act, Assert
+        await this.ExecuteTestAsync(
+            displayName: nameof(SetMultipleVariablesWithNullValuesAsync),
+            assignments: [
+                new AssignmentCase("NullVar1", null, FormulaValue.NewBlank()),
+                new AssignmentCase("NormalVar", new StringDataValue("NotNull"), FormulaValue.New("NotNull")),
+                new AssignmentCase("NullVar2", null, FormulaValue.NewBlank())
+            ]);
+    }
+
+    [Fact]
+    public async Task SetMultipleVariablesUpdateExistingAsync()
+    {
+        // Arrange
+        this.State.Set("ExistingVar1", FormulaValue.New(999));
+        this.State.Set("ExistingVar2", FormulaValue.New("OldValue"));
+
+        // Act, Assert
+        await this.ExecuteTestAsync(
+            displayName: nameof(SetMultipleVariablesUpdateExistingAsync),
+            assignments: [
+                new AssignmentCase("ExistingVar1", new NumberDataValue(111), FormulaValue.New(111)),
+                new AssignmentCase("ExistingVar2", new StringDataValue("NewValue"), FormulaValue.New("NewValue")),
+                new AssignmentCase("NewVar", new BooleanDataValue(false), FormulaValue.New(false))
+            ]);
+    }
+
+    [Fact]
+    public async Task SetMultipleVariablesEmptyAssignmentsAsync()
+    {
+        // Arrange
+        SetMultipleVariables model = this.CreateModel(nameof(SetMultipleVariablesEmptyAssignmentsAsync), []);
+
+        // Arrange, Act, Assert
+        Assert.Throws<DeclarativeModelException>(() =>
+        {
+            // Empty variables assignment should fail RequiredProperties validation.
+            _ = new SetMultipleVariablesExecutor(model, this.State);
+        });
+    }
+
+    private async Task ExecuteTestAsync(string displayName, AssignmentCase[] assignments)
+    {
+        // Arrange
+        SetMultipleVariables model = this.CreateModel(displayName, assignments);
+
+        // Act
+        SetMultipleVariablesExecutor action = new(model, this.State);
+        await this.ExecuteAsync(action);
+
+        // Assert
+        VerifyModel(model, action);
+        foreach (AssignmentCase assignment in assignments)
+        {
+            this.VerifyState(assignment.VariableName, assignment.ExpectedValue);
+        }
+    }
+
+    private SetMultipleVariables CreateModel(string displayName, AssignmentCase[] assignments)
+    {
+        SetMultipleVariables.Builder actionBuilder = new()
+        {
+            Id = this.CreateActionId(),
+            DisplayName = this.FormatDisplayName(displayName),
+        };
+
+        foreach (AssignmentCase assignment in assignments)
+        {
+            ValueExpression.Builder? valueExpressionBuilder = assignment.ValueExpression switch
+            {
+                null => null,
+                DataValue dataValue => new ValueExpression.Builder(ValueExpression.Literal(dataValue)),
+                ValueExpression valueExpression => new ValueExpression.Builder(valueExpression),
+                _ => throw new System.ArgumentException($"Unsupported value type: {assignment.ValueExpression?.GetType().Name}")
+            };
+
+            actionBuilder.Assignments.Add(new VariableAssignment.Builder()
+            {
+                Variable = PropertyPath.Create(FormatVariablePath(assignment.VariableName)),
+                Value = valueExpressionBuilder,
+            });
+        }
+
+        return AssignParent<SetMultipleVariables>(actionBuilder);
+    }
+
+    private sealed record AssignmentCase(string VariableName, object? ValueExpression, FormulaValue ExpectedValue);
+}