[Autocomplete] Prevent shrink animation in uncontrolled Autocomplete when default value is set

packages/mui-material/src/useAutocomplete/useAutocomplete.js

@@ -61,6 +61,14 @@ const defaultIsActiveElementInListbox = (listboxRef) =>
 
 const MULTIPLE_DEFAULT_VALUE = [];
 
+function getInputValue(value, multiple, getOptionLabel) {
+  if (multiple || value == null) {
+    return '';
+  }
+  const optionLabel = getOptionLabel(value);
+  return typeof optionLabel === 'string' ? optionLabel : '';
+}
+
 function useAutocomplete(props) {
   const {
     // eslint-disable-next-line @typescript-eslint/naming-convention
@@ -137,14 +145,20 @@ function useAutocomplete(props) {
   const defaultHighlighted = autoHighlight ? 0 : -1;
   const highlightedIndexRef = React.useRef(defaultHighlighted);
 
+  // Calculate the initial inputValue on mount only.
+  // Using useRef since defaultValue doesn't need to update inputValue dynamically.
+  const initialInputValue = React.useRef(
+    getInputValue(defaultValue, multiple, getOptionLabel),
+  ).current;
+
   const [value, setValueState] = useControlled({
     controlled: valueProp,
     default: defaultValue,
     name: componentName,
   });
   const [inputValue, setInputValueState] = useControlled({
     controlled: inputValueProp,
-    default: '',
+    default: initialInputValue,
     name: componentName,
     state: 'inputValue',
   });
@@ -159,15 +173,7 @@ function useAutocomplete(props) {
       if (!isOptionSelected && !clearOnBlur) {
         return;
       }
-      let newInputValue;
-      if (multiple) {
-        newInputValue = '';
-      } else if (newValue == null) {
-        newInputValue = '';
-      } else {
-        const optionLabel = getOptionLabel(newValue);
-        newInputValue = typeof optionLabel === 'string' ? optionLabel : '';
-      }
+      const newInputValue = getInputValue(newValue, multiple, getOptionLabel);
 
       if (inputValue === newInputValue) {
         return;

packages/mui-material/src/useAutocomplete/useAutocomplete.test.js

@@ -395,4 +395,24 @@ describe('useAutocomplete', () => {
       fireEvent.click(button);
     }).not.to.throw();
   });
+
+  describe('prop: defaultValue', () => {
+    it('should not trigger onInputChange when defaultValue is provided', () => {
+      const onInputChange = spy();
+      const defaultValue = 'foo';
+
+      function Test() {
+        const { getInputProps } = useAutocomplete({
+          defaultValue,
+          onInputChange,
+          options: ['foo', 'bar'],
+        });
+
+        return <input {...getInputProps()} />;
+      }
+
+      render(<Test />);
+      expect(onInputChange.callCount).to.equal(0);
+    });
+  });
 });