From 87a3b76c76f5e2cb00f1f75f8743170e0db6fa0e Mon Sep 17 00:00:00 2001
From: Jeremy Elbourn <jelbourn@google.com>
Date: Fri, 21 May 2021 15:27:50 -0700
Subject: [PATCH] fix(material/schematics): don't insert duplicate `@use`
 statements in themingApi

In the case where a file has mixed legacy and new theming API usage, the script would
add an extra duplicate `@use` statement.
---
 .../migrations/theming-api-v12/migration.ts     |  6 ++++++
 .../test-cases/v12/misc/theming-api-v12.spec.ts | 17 +++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/material/schematics/ng-update/migrations/theming-api-v12/migration.ts b/src/material/schematics/ng-update/migrations/theming-api-v12/migration.ts
index e662e1ec504b..c72ce8a7ce5b 100644
--- a/src/material/schematics/ng-update/migrations/theming-api-v12/migration.ts
+++ b/src/material/schematics/ng-update/migrations/theming-api-v12/migration.ts
@@ -207,6 +207,12 @@ function renameSymbols(content: string,
 /** Inserts an `@use` statement in a string. */
 function insertUseStatement(content: string, importPath: string, importsToIgnore: string[],
                             namespace: string): string {
+  // If the content already has the `@use` import, we don't need to add anything.
+  const alreadyImportedPattern = new RegExp(`@use +['"]${importPath}['"]`, 'g');
+  if (alreadyImportedPattern.test(content)) {
+    return content;
+  }
+
   // We want to find the first import that isn't in the list of ignored imports or find nothing,
   // because the imports being replaced might be the only ones in the file and they can be further
   // down. An easy way to do this is to replace the imports with a random character and run
diff --git a/src/material/schematics/ng-update/test-cases/v12/misc/theming-api-v12.spec.ts b/src/material/schematics/ng-update/test-cases/v12/misc/theming-api-v12.spec.ts
index c8446b701671..32cfc9abc820 100644
--- a/src/material/schematics/ng-update/test-cases/v12/misc/theming-api-v12.spec.ts
+++ b/src/material/schematics/ng-update/test-cases/v12/misc/theming-api-v12.spec.ts
@@ -737,4 +737,21 @@ describe('v12 theming API migration', () => {
       `@include mat.core();`,
     ]);
   });
+
+  it('should not add duplicate @use statements', async () => {
+    writeLines(THEME_PATH, [
+      `@use '~@angular/material' as mat;`,
+      `@import '~@angular/material/theming';`,
+      `$something: mat.$red-palette;`,
+      `$another: $mat-pink;`,
+    ]);
+
+    await runMigration();
+
+    expect(splitFile(THEME_PATH)).toEqual([
+      `@use '~@angular/material' as mat;`,
+      `$something: mat.$red-palette;`,
+      `$another: mat.$pink-palette;`,
+    ]);
+  });
 });