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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using Microsoft.AspNetCore.Mvc.ModelBinding;
namespace Microsoft.AspNetCore.Mvc.Rendering;
/// <summary>
/// Test the <see cref="HtmlHelperDisplayNameExtensions" /> class.
/// </summary>
public class HtmlHelperDisplayNameExtensionsTest
{
[Fact]
public void DisplayNameHelpers_ReturnEmptyForModel()
{
// Arrange
var helper = DefaultTemplatesUtilities.GetHtmlHelper();
var enumerableHelper =
DefaultTemplatesUtilities.GetHtmlHelper<IEnumerable<DefaultTemplatesUtilities.ObjectTemplateModel>>(model: null);
// Act
var displayNameResult = helper.DisplayName(expression: string.Empty);
var displayNameNullResult = helper.DisplayName(expression: null); // null is another alias for current model
var displayNameForResult = helper.DisplayNameFor(m => m);
var displayNameForEnumerableModelResult = enumerableHelper.DisplayNameFor(m => m);
var displayNameForModelResult = helper.DisplayNameForModel();
// Assert
Assert.Empty(displayNameResult);
Assert.Empty(displayNameNullResult);
Assert.Empty(displayNameForResult);
Assert.Empty(displayNameForEnumerableModelResult);
Assert.Empty(displayNameForModelResult);
}
[Fact]
public void DisplayNameHelpers_ReturnPropertyName()
{
// Arrange
var helper = DefaultTemplatesUtilities.GetHtmlHelper();
var enumerableHelper = DefaultTemplatesUtilities.GetHtmlHelperForEnumerable();
// Act
var displayNameResult = helper.DisplayName("Property1");
var displayNameForResult = helper.DisplayNameFor(m => m.Property1);
var displayNameForEnumerableResult = enumerableHelper.DisplayNameFor(m => m.Property1);
// Assert
Assert.Equal("Property1", displayNameResult);
Assert.Equal("Property1", displayNameForResult);
Assert.Equal("Property1", displayNameForEnumerableResult);
}
// If the metadata is for a type (not property), then DisplayName(expression) will evaluate the expression
[Fact]
public void DisplayNameHelpers_DisplayName_Evaluates_Expression()
{
// Arrange
var helper = DefaultTemplatesUtilities.GetHtmlHelper();
helper.ViewData["value"] = "testvalue";
// Act
var displayNameResult = helper.DisplayName(expression: "value");
// Assert
Assert.Equal("value", displayNameResult);
}
[Fact]
public void DisplayNameHelpers_ReturnPropertyName_ForNestedProperty()
{
// Arrange
var helper = DefaultTemplatesUtilities.GetHtmlHelper<OuterClass>(model: null);
var enumerableHelper = DefaultTemplatesUtilities.GetHtmlHelperForEnumerable<OuterClass>(model: null);
// Act
var displayNameResult = helper.DisplayName("Inner.Id");
var displayNameForResult = helper.DisplayNameFor(m => m.Inner.Id);
var displayNameForEnumerableResult = enumerableHelper.DisplayNameFor(m => m.Inner.Id);
// Assert
Assert.Equal("Id", displayNameResult);
Assert.Equal("Id", displayNameForResult);
Assert.Equal("Id", displayNameForEnumerableResult);
}
[Theory]
[InlineData("")] // Empty display name wins over non-empty property name.
[InlineData("Custom display name from metadata")]
public void DisplayNameHelpers_ReturnDisplayName_IfNonNull(string displayName)
{
// Arrange
var provider = new TestModelMetadataProvider();
provider
.ForType<DefaultTemplatesUtilities.ObjectTemplateModel>()
.DisplayDetails(dd => dd.DisplayName = () => displayName);
var helper = DefaultTemplatesUtilities.GetHtmlHelper(provider: provider);
var enumerableHelper = DefaultTemplatesUtilities.GetHtmlHelperForEnumerable(provider: provider);
// Act
var displayNameResult = helper.DisplayName(expression: string.Empty);
var displayNameForResult = helper.DisplayNameFor(m => m);
var displayNameForEnumerableResult = enumerableHelper.DisplayNameFor((DefaultTemplatesUtilities.ObjectTemplateModel m) => m);
var displayNameForModelResult = helper.DisplayNameForModel();
// Assert
Assert.Equal(displayName, displayNameResult);
Assert.Equal(displayName, displayNameForResult);
Assert.Equal(displayName, displayNameForEnumerableResult);
Assert.Equal(displayName, displayNameForModelResult);
}
[Theory]
[InlineData("")]
[InlineData("Custom display name from metadata")]
public void DisplayNameHelpers_ReturnDisplayNameForProperty_IfNonNull(string displayName)
{
// Arrange
var provider = new TestModelMetadataProvider();
provider
.ForProperty<DefaultTemplatesUtilities.ObjectTemplateModel>("Property1")
.DisplayDetails(dd => dd.DisplayName = () => displayName);
var helper = DefaultTemplatesUtilities.GetHtmlHelper(provider: provider);
var enumerableHelper = DefaultTemplatesUtilities.GetHtmlHelperForEnumerable(provider: provider);
// Act
var displayNameResult = helper.DisplayName("Property1");
var displayNameForResult = helper.DisplayNameFor(m => m.Property1);
var displayNameForEnumerableResult = enumerableHelper.DisplayNameFor(m => m.Property1);
// Assert
Assert.Equal(displayName, displayNameResult);
Assert.Equal(displayName, displayNameForResult);
Assert.Equal(displayName, displayNameForEnumerableResult);
}
[Theory]
[InlineData("A", "A")]
[InlineData("A[23]", "A[23]")]
[InlineData("A[0].B", "B")]
[InlineData("A.B.C.D", "D")]
public void DisplayName_ReturnsRightmostExpressionSegment_IfPropertiesNotFound(
string expression,
string expectedResult)
{
// Arrange
var helper = DefaultTemplatesUtilities.GetHtmlHelper();
// Act
var result = helper.DisplayName(expression);
// Assert
// DisplayName() falls back to expression name when DisplayName and PropertyName are null.
Assert.Equal(expectedResult, result);
}
[Fact]
public void DisplayNameFor_ThrowsInvalidOperation_IfExpressionUnsupported()
{
// Arrange
var helper = DefaultTemplatesUtilities.GetHtmlHelper();
// Act & Assert
var exception = Assert.Throws<InvalidOperationException>(
() => helper.DisplayNameFor(model => new { foo = "Bar" }));
Assert.Equal(
"Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions.",
exception.Message);
}
[Fact]
public void EnumerableDisplayNameFor_ThrowsInvalidOperation_IfExpressionUnsupported()
{
// Arrange
var helper =
DefaultTemplatesUtilities.GetHtmlHelper<IEnumerable<DefaultTemplatesUtilities.ObjectTemplateModel>>(model: null);
// Act & Assert
var exception = Assert.Throws<InvalidOperationException>(
() => helper.DisplayNameFor(model => new { foo = "Bar" }));
Assert.Equal(
"Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions.",
exception.Message);
}
[Fact]
public void DisplayNameFor_ReturnsVariableName()
{
// Arrange
var unknownKey = "this is a dummy parameter value";
var helper = DefaultTemplatesUtilities.GetHtmlHelper();
// Act
var result = helper.DisplayNameFor(model => unknownKey);
// Assert
Assert.Equal("unknownKey", result);
}
[Fact]
public void EnumerableDisplayNameFor_ReturnsVariableName()
{
// Arrange
var unknownKey = "this is a dummy parameter value";
var helper =
DefaultTemplatesUtilities.GetHtmlHelper<IEnumerable<DefaultTemplatesUtilities.ObjectTemplateModel>>(model: null);
// Act
var result = helper.DisplayNameFor(model => unknownKey);
// Assert
Assert.Equal("unknownKey", result);
}
private sealed class InnerClass
{
public int Id { get; set; }
}
private sealed class OuterClass
{
public InnerClass Inner { get; set; }
}
}
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