fix(material/schematics): add attr for multi-line start tags (#24586)

* add logic for handling multi-line start tags in #addAttribute
* unit tested
* delete unused template-migration.spec.ts file

Author: wagnermaciel

src/material/schematics/ng-generate/mdc-migration/rules/components/card/card-template.spec.ts

@@ -90,4 +90,24 @@ describe('card template migrator', () => {
       `,
     );
   });
+
+  it('should match indentation', async () => {
+    await runMigrationTest(
+      `
+        <mat-card
+          class="some card"
+          aria-label="some card"
+          aria-describedby="some card"
+        ></mat-card>
+      `,
+      `
+        <mat-card
+          appearance="outlined"
+          class="some card"
+          aria-label="some card"
+          aria-describedby="some card"
+        ></mat-card>
+      `,
+    );
+  });
 });

src/material/schematics/ng-generate/mdc-migration/rules/template-migration.spec.ts

@@ -119,4 +119,47 @@ describe('#visitElements', () => {
       expect(html).toBe('<a attr2="val2" attr1="val1"></a>');
     });
   });
+
+  it('should match indentation', async () => {
+    runAddAttributeTest(
+      `
+        <a
+          class="a"
+          aria-label="a"
+          aria-describedby="a"
+        ></a>
+      `,
+      `
+        <a
+          attr="val"
+          class="a"
+          aria-label="a"
+          aria-describedby="a"
+        ></a>
+      `,
+    );
+  });
+
+  it('should match indentation w/ multiple attrs', async () => {
+    let html = `
+      <a
+        class="a"
+        aria-label="a"
+        aria-describedby="a"
+      ></a>
+    `;
+    visitElements(parseTemplate(html).nodes, undefined, node => {
+      html = addAttribute(html, node, 'attr1', 'val1');
+      html = addAttribute(html, node, 'attr2', 'val2');
+    });
+    expect(html).toBe(`
+      <a
+        attr2="val2"
+        attr1="val1"
+        class="a"
+        aria-label="a"
+        aria-describedby="a"
+      ></a>
+    `);
+  });
 });

src/material/schematics/ng-generate/mdc-migration/rules/tree-traversal.spec.ts

@@ -98,7 +98,16 @@ export function addAttribute(
   const index = node.startSourceSpan.start.offset + node.name.length + 1;
   const prefix = html.slice(0, index);
   const suffix = html.slice(index);
-  return prefix + ` ${name}="${value}"` + suffix;
+
+  if (node.startSourceSpan.start.line === node.startSourceSpan.end.line) {
+    return prefix + ` ${name}="${value}"` + suffix;
+  }
+
+  const attr = node.attributes[0];
+  const ctx = attr.sourceSpan.start.getContext(attr.sourceSpan.start.col + 1, 1)!;
+  const indentation = ctx.before;
+
+  return prefix + indentation + `${name}="${value}"` + suffix;
 }
 
 /**