DAS plugins: Make the fix offset a range over the diagnostic

Fixes #61491

Change-Id: I2616006b7ac1ba645e4bed3caeb0781f04864feb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/449362
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>

Author: srawlins

pkg/analysis_server_plugin/lib/src/plugin_server.dart

@@ -195,9 +195,13 @@ class PluginServer {
       return protocol.EditGetFixesResult(const []);
     }
 
-    var lintAtOffset = errors.where(
-      (error) => error.diagnostic.offset == offset,
-    );
+    var lineInfo = unitResult.lineInfo;
+    var requestLine = lineInfo.getLocation(offset).lineNumber;
+
+    var lintAtOffset = errors.where((error) {
+      var errorLine = lineInfo.getLocation(error.diagnostic.offset).lineNumber;
+      return errorLine == requestLine;
+    });
     if (lintAtOffset.isEmpty) return protocol.EditGetFixesResult(const []);
 
     var errorFixesList = <protocol.AnalysisErrorFixes>[];

pkg/analysis_server_plugin/test/src/plugin_server_test.dart

@@ -149,6 +149,34 @@ bool b = false;
     expect(fixes.fixes, hasLength(4));
   }
 
+  Future<void> test_handleEditGetFixes_afterLine() async {
+    writeAnalysisOptionsWithPlugin();
+    newFile(filePath, 'bool b = false;\n\n');
+    await channel.sendRequest(
+      protocol.AnalysisSetContextRootsParams([contextRoot]),
+    );
+
+    var result = await pluginServer.handleEditGetFixes(
+      protocol.EditGetFixesParams(filePath, 'bool b = false;\n'.length),
+    );
+    expect(result.fixes, isEmpty);
+  }
+
+  Future<void> test_handleEditGetFixes_onSameLine() async {
+    writeAnalysisOptionsWithPlugin();
+    newFile(filePath, 'bool b = false;');
+    await channel.sendRequest(
+      protocol.AnalysisSetContextRootsParams([contextRoot]),
+    );
+
+    var result = await pluginServer.handleEditGetFixes(
+      protocol.EditGetFixesParams(filePath, 'bool b = fa'.length),
+    );
+    var fixes = result.fixes.single;
+    // The WrapInQuotes fix plus three "ignore diagnostic" fixes.
+    expect(fixes.fixes, hasLength(4));
+  }
+
   Future<void> test_handleEditGetFixes_viaSendRequest() async {
     writeAnalysisOptionsWithPlugin();
     newFile(filePath, 'bool b = false;');