Implement an initializer of CodeAction with the FixIt from swift-syntax

Finetune the code

Finetune the code

Finetune the code

Update the code per comments

Use location marker instead of hard coded indexes

Update the test to align the code convention

Rename a variable

Correct unit tests

Format the code

Update Package.swift

Author: joehsieh

Sources/SourceKitLSP/Swift/Diagnostic.swift

@@ -44,22 +44,10 @@ extension CodeAction {
     if let fromNote = fromNote {
       title = fromNote
     } else {
-      guard let startIndex = snapshot.index(of: edits[0].range.lowerBound),
-        let endIndex = snapshot.index(of: edits[0].range.upperBound),
-        startIndex <= endIndex,
-        snapshot.text.indices.contains(startIndex),
-        endIndex <= snapshot.text.endIndex
-      else {
-        logger.fault("position mapped, but indices failed for edit range \(String(reflecting: edits[0]))")
+      guard let generatedTitle = Self.title(for: edits, in: snapshot) else {
         return nil
       }
-      let oldText = String(snapshot.text[startIndex..<endIndex])
-      let description = Self.fixitTitle(replace: oldText, with: edits[0].newText)
-      if edits.count == 1 {
-        title = description
-      } else {
-        title = description + "..."
-      }
+      title = generatedTitle
     }
 
     self.init(
@@ -71,10 +59,43 @@ extension CodeAction {
   }
 
   init?(_ fixIt: FixIt, in snapshot: DocumentSnapshot) {
-    // FIXME: Once https://github.com/apple/swift-syntax/pull/2226 is merged and
-    // FixItApplier is public, use it to compute the edits that should be
-    // applied to the source.
-    return nil
+    var textEdits = [TextEdit]()
+    for edit in fixIt.edits {
+      guard let startPosition = snapshot.position(of: edit.range.lowerBound),
+        let endPosition = snapshot.position(of: edit.range.upperBound)
+      else {
+        continue
+      }
+      textEdits.append(TextEdit(range: startPosition..<endPosition, newText: edit.replacement))
+    }
+
+    self.init(
+      title: fixIt.message.message.withFirstLetterUppercased(),
+      kind: .quickFix,
+      diagnostics: nil,
+      edit: WorkspaceEdit(changes: [snapshot.uri: textEdits])
+    )
+  }
+
+  private static func title(for edits: [TextEdit], in snapshot: DocumentSnapshot) -> String? {
+    if edits.isEmpty {
+      return nil
+    }
+    guard let startIndex = snapshot.index(of: edits[0].range.lowerBound),
+      let endIndex = snapshot.index(of: edits[0].range.upperBound),
+      startIndex <= endIndex,
+      snapshot.text.indices.contains(startIndex),
+      endIndex <= snapshot.text.endIndex
+    else {
+      logger.fault("position mapped, but indices failed for edit range \(String(reflecting: edits[0]))")
+      return nil
+    }
+    let oldText = String(snapshot.text[startIndex..<endIndex])
+    let description = Self.fixitTitle(replace: oldText, with: edits[0].newText)
+    if edits.count == 1 {
+      return description
+    }
+    return description + "..."
   }
 
   /// Describe a fixit's edit briefly.

Tests/SourceKitLSPTests/CodeActionTests.swift

@@ -425,4 +425,51 @@ final class CodeActionTests: XCTestCase {
 
     try await fulfillmentOfOrThrow([editReceived])
   }
+
+  func testCodeActionForFixItsProducedBySwiftSyntax() async throws {
+    let ws = try await MultiFileTestWorkspace(files: [
+      "test.swift": "protocol 1️⃣Multi 2️⃣ident 3️⃣{}",
+      "compile_commands.json": "[]",
+    ])
+
+    let (uri, positions) = try ws.openDocument("test.swift")
+
+    let report = try await ws.testClient.send(DocumentDiagnosticsRequest(textDocument: TextDocumentIdentifier(uri)))
+    guard case .full(let fullReport) = report else {
+      XCTFail("Expected full diagnostics report")
+      return
+    }
+
+    XCTAssertEqual(fullReport.items.count, 1)
+    let diagnostic = try XCTUnwrap(fullReport.items.first)
+    let codeActions = try XCTUnwrap(diagnostic.codeActions)
+
+    let expectedCodeActions = [
+      CodeAction(
+        title: "Join the identifiers together",
+        kind: .quickFix,
+        edit: WorkspaceEdit(
+          changes: [
+            uri: [
+              TextEdit(range: positions["1️⃣"]..<positions["2️⃣"], newText: "Multiident "),
+              TextEdit(range: positions["2️⃣"]..<positions["3️⃣"], newText: ""),
+            ]
+          ]
+        )
+      ),
+      CodeAction(
+        title: "Join the identifiers together with camel-case",
+        kind: .quickFix,
+        edit: WorkspaceEdit(
+          changes: [
+            uri: [
+              TextEdit(range: positions["1️⃣"]..<positions["2️⃣"], newText: "MultiIdent "),
+              TextEdit(range: positions["2️⃣"]..<positions["3️⃣"], newText: ""),
+            ]
+          ]
+        )
+      ),
+    ]
+    XCTAssertEqual(expectedCodeActions, codeActions)
+  }
 }