add layout test

[youge325]

新增 layout 接口测试

[Copilot]

Pull request overview

This PR adds comprehensive test coverage for the tensor layout interface, validating layout functionality across multiple namespaces (c10, at, torch) and testing layout enum properties and output stream operations.

Key Changes:

• Added <sstream> include for output stream testing
• Implemented 6 new test cases covering layout constants, enum values, and stream operators
• Tests verify layout consistency across c10, at, and torch namespaces

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[Copilot]

The test LayoutOutputStream contains repetitive code that clears and writes to the same ostringstream. This reduces maintainability. Consider using a helper function or restructuring the test to reduce duplication.

Suggested change

	oss.str("");
	oss << c10::Layout::Strided;
	EXPECT_EQ(oss.str(), "Strided");
	oss.str("");
	oss << c10::Layout::Sparse;
	EXPECT_EQ(oss.str(), "Sparse");
	oss.str("");
	oss << c10::Layout::SparseCsr;
	EXPECT_EQ(oss.str(), "SparseCsr");
	oss.str("");
	oss << c10::Layout::SparseCsc;
	EXPECT_EQ(oss.str(), "SparseCsc");
	oss.str("");
	oss << c10::Layout::SparseBsr;
	EXPECT_EQ(oss.str(), "SparseBsr");
	oss.str("");
	oss << c10::Layout::SparseBsc;
	EXPECT_EQ(oss.str(), "SparseBsc");
	oss.str("");
	oss << c10::Layout::Mkldnn;
	EXPECT_EQ(oss.str(), "Mkldnn");
	oss.str("");
	oss << c10::Layout::Jagged;
	EXPECT_EQ(oss.str(), "Jagged");
	auto checkLayoutToString = [&oss](c10::Layout layout, const std::string& expected) {
	oss.str("");
	oss.clear();
	oss << layout;
	EXPECT_EQ(oss.str(), expected);
	};
	checkLayoutToString(c10::Layout::Strided, "Strided");
	checkLayoutToString(c10::Layout::Sparse, "Sparse");
	checkLayoutToString(c10::Layout::SparseCsr, "SparseCsr");
	checkLayoutToString(c10::Layout::SparseCsc, "SparseCsc");
	checkLayoutToString(c10::Layout::SparseBsr, "SparseBsr");
	checkLayoutToString(c10::Layout::SparseBsc, "SparseBsc");
	checkLayoutToString(c10::Layout::Mkldnn, "Mkldnn");
	checkLayoutToString(c10::Layout::Jagged, "Jagged");

[Copilot]

Testing the underlying enum values (casting to int8_t) creates a brittle test that depends on the internal representation of the enum. If the enum ordering changes in PyTorch/ATen, this test will fail. Consider removing this test or documenting why the specific enum values must remain stable.

Suggested change

	// 测试 layout 枚举值
	TEST_F(TensorTest, LayoutEnumValues) {
	// 测试 Layout 枚举的底层值
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::Strided), 0);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::Sparse), 1);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::SparseCsr), 2);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::Mkldnn), 3);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::SparseCsc), 4);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::SparseBsr), 5);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::SparseBsc), 6);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::Jagged), 7);
	EXPECT_EQ(static_cast<int8_t>(c10::Layout::NumOptions), 8);
	}