From c3b1725a2dacbf021324dcd59d08a206d293d640 Mon Sep 17 00:00:00 2001
From: Matt Bierner <matb@microsoft.com>
Date: Wed, 20 May 2020 15:31:16 -0700
Subject: [PATCH] Make sure implement interface is prioritized over remove
 unused

Fixes #94212
---
 .../src/features/quickFix.ts                   |  4 +++-
 .../src/test/quickFix.test.ts                  | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/extensions/typescript-language-features/src/features/quickFix.ts b/extensions/typescript-language-features/src/features/quickFix.ts
index 204c2896d50..cc8202e2f15 100644
--- a/extensions/typescript-language-features/src/features/quickFix.ts
+++ b/extensions/typescript-language-features/src/features/quickFix.ts
@@ -344,7 +344,7 @@ const preferredFixes = new Map<string, { readonly value: number, readonly thereC
 	[fixNames.constructorForDerivedNeedSuperCall, { value: 1 }],
 	[fixNames.extendsInterfaceBecomesImplements, { value: 1 }],
 	[fixNames.awaitInSyncFunction, { value: 1 }],
-	[fixNames.classIncorrectlyImplementsInterface, { value: 1 }],
+	[fixNames.classIncorrectlyImplementsInterface, { value: 3 }],
 	[fixNames.unreachableCode, { value: 1 }],
 	[fixNames.unusedIdentifier, { value: 1 }],
 	[fixNames.forgottenThisPropertyAccess, { value: 1 }],
@@ -378,6 +378,8 @@ function isPreferredFix(
 		const otherFixPriority = preferredFixes.get(otherAction.tsAction.fixName);
 		if (!otherFixPriority || otherFixPriority.value < fixPriority.value) {
 			return true;
+		} else if (otherFixPriority.value > fixPriority.value) {
+			return false;
 		}
 
 		if (fixPriority.thereCanOnlyBeOne && action.tsAction.fixName === otherAction.tsAction.fixName) {
diff --git a/extensions/typescript-language-features/src/test/quickFix.test.ts b/extensions/typescript-language-features/src/test/quickFix.test.ts
index 70be9b5ebef..45ad4f7c2c1 100644
--- a/extensions/typescript-language-features/src/test/quickFix.test.ts
+++ b/extensions/typescript-language-features/src/test/quickFix.test.ts
@@ -104,6 +104,24 @@ suite('TypeScript Quick Fix', () => {
 		const ignoreFixes = fixes?.filter(x => x.title === 'Ignore this error message');
 		assert.strictEqual(ignoreFixes?.length, 1);
 	});
+
+	test('Should prioritize implement interface over remove unused #94212', async () => {
+		const testDocumentUri = workspaceFile('foo.ts');
+		const editor = await createTestEditor(testDocumentUri,
+			`export interface IFoo { value: string; }`,
+			`class Foo implements IFoo { }`);
+
+		await wait(3000);
+
+		const fixes = await vscode.commands.executeCommand<vscode.CodeAction[]>('vscode.executeCodeActionProvider',
+			testDocumentUri,
+			editor.document.lineAt(1).range
+		);
+
+		assert.strictEqual(fixes?.length, 2);
+		assert.strictEqual(fixes![0].title, `Implement interface 'IFoo'`);
+		assert.strictEqual(fixes![1].title, `Remove unused declaration for: 'Foo'`);
+	});
 });