ensure that all-unset alignments and no alignments compare equal

Author: QuietMisdreavus

Sources/SwiftDocC/Model/Rendering/Content/RenderBlockContent.swift

@@ -233,7 +233,7 @@ public enum RenderBlockContent: Equatable {
     }
 
     /// A table that contains a list of row data.
-    public struct Table: Equatable {
+    public struct Table {
         /// The style of header in this table.
         public var header: HeaderType
         /// The text alignment of each column in this table.
@@ -525,6 +525,30 @@ public enum RenderBlockContent: Equatable {
     }
 }
 
+extension RenderBlockContent.Table: Equatable {
+    public static func == (lhs: RenderBlockContent.Table, rhs: RenderBlockContent.Table) -> Bool {
+        guard lhs.header == rhs.header
+                && lhs.extendedData == rhs.extendedData
+                && lhs.metadata == rhs.metadata
+                && lhs.rows == rhs.rows
+        else {
+            return false
+        }
+
+        var lhsAlignments = lhs.alignments
+        if let align = lhsAlignments, align.allSatisfy({ $0 == .unset }) {
+            lhsAlignments = nil
+        }
+
+        var rhsAlignments = rhs.alignments
+        if let align = rhsAlignments, align.allSatisfy({ $0 == .unset }) {
+            rhsAlignments = nil
+        }
+
+        return lhsAlignments == rhsAlignments
+    }
+}
+
 // Writing a manual Codable implementation for tables because the encoding of `extendedData` does
 // not follow from the struct layout.
 extension RenderBlockContent.Table: Codable {

Tests/SwiftDocCTests/Model/RenderContentMetadataTests.swift

@@ -200,6 +200,80 @@ class RenderContentMetadataTests: XCTestCase {
 
         try assertRoundTripCoding(renderedTable)
     }
+
+    /// Verifies that a table with `nil` alignments and a table with all-unset alignments still compare as equal.
+    func testRenderedTableEquality() throws {
+        let (bundle, context) = try testBundleAndContext(named: "TestBundle")
+        var renderContentCompiler = RenderContentCompiler(context: context, bundle: bundle, identifier: ResolvedTopicReference(bundleIdentifier: bundle.identifier, path: "/path", fragment: nil, sourceLanguage: .swift))
+
+        let source = """
+        | Column 1  | Column 2 |
+        | ------------- | ------------- |
+        | Cell 1 | Cell 2 |
+        | Cell 3 | Cell 4 |
+        """
+        let document = Document(parsing: source)
+
+        let result = try XCTUnwrap(renderContentCompiler.visit(document.child(at: 0)!))
+        let renderedTable = try XCTUnwrap(result.first as? RenderBlockContent)
+        guard case let .table(decodedTable) = renderedTable else {
+            XCTFail("Unexpected RenderBlockContent element")
+            return
+        }
+        XCTAssertNil(decodedTable.alignments)
+        var modifiedTable = decodedTable
+        modifiedTable.alignments = [.unset, .unset]
+
+        XCTAssertEqual(decodedTable, modifiedTable)
+    }
+
+    /// Verifies that two tables with otherwise-identical contents but different column alignments compare as unequal.
+    func testRenderedTableInequality() throws {
+        let (bundle, context) = try testBundleAndContext(named: "TestBundle")
+        var renderContentCompiler = RenderContentCompiler(context: context, bundle: bundle, identifier: ResolvedTopicReference(bundleIdentifier: bundle.identifier, path: "/path", fragment: nil, sourceLanguage: .swift))
+
+        let decodedTableWithUnsetColumns: RenderBlockContent.Table
+        do {
+            let source = """
+            | Column 1  | Column 2 |
+            | ------------- | ------------- |
+            | Cell 1 | Cell 2 |
+            | Cell 3 | Cell 4 |
+            """
+            let document = Document(parsing: source)
+
+            let result = try XCTUnwrap(renderContentCompiler.visit(document.child(at: 0)!))
+            let renderedTable = try XCTUnwrap(result.first as? RenderBlockContent)
+            guard case let .table(decodedTable) = renderedTable else {
+                XCTFail("Unexpected RenderBlockContent element")
+                return
+            }
+            decodedTableWithUnsetColumns = decodedTable
+        }
+
+        let decodedTableWithLeftColumns: RenderBlockContent.Table
+        do {
+            let source = """
+            | Column 1  | Column 2 |
+            | :------------ | :------------ |
+            | Cell 1 | Cell 2 |
+            | Cell 3 | Cell 4 |
+            """
+            let document = Document(parsing: source)
+
+            // Verifies that a markdown table renders correctly.
+
+            let result = try XCTUnwrap(renderContentCompiler.visit(document.child(at: 0)!))
+            let renderedTable = try XCTUnwrap(result.first as? RenderBlockContent)
+            guard case let .table(decodedTable) = renderedTable else {
+                XCTFail("Unexpected RenderBlockContent element")
+                return
+            }
+            decodedTableWithLeftColumns = decodedTable
+        }
+
+        XCTAssertNotEqual(decodedTableWithUnsetColumns, decodedTableWithLeftColumns)
+    }
 
     func testStrikethrough() throws {
         let (bundle, context) = try testBundleAndContext(named: "TestBundle")