Fix adjustsFontSizeToFit for strings with a single character

packages/react-native/Libraries/Text/Text/NSTextStorage+FontScaling.m

@@ -66,6 +66,15 @@ - (RCTTextSizeComparisonOptions)compareToSize:(CGSize)size thresholdRatio:(CGFlo
   NSLayoutManager *layoutManager = self.layoutManagers.firstObject;
   NSTextContainer *textContainer = layoutManager.textContainers.firstObject;
 
+  // A workaround for truncatedGlyphRangeInLineFragmentForGlyphAtIndex returning NSNotFound when text has only
+  // one character and it gets truncated
+  if ([self length] == 1) {
+    CGSize characterSize = [[self string] sizeWithAttributes:[self attributesAtIndex:0 effectiveRange:nil]];
+    if (characterSize.width > size.width) {
+      return RCTTextSizeComparisonLarger;
+    }
+  }
+
   [layoutManager ensureLayoutForTextContainer:textContainer];
 
   // Does it fit the text container?

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/text/TextLayoutManager.java

@@ -630,7 +630,8 @@ private static Layout createLayout(
                 && maximumNumberOfLines != 0
                 && layout.getLineCount() > maximumNumberOfLines)
             || (heightYogaMeasureMode != YogaMeasureMode.UNDEFINED
-                && layout.getHeight() > height))) {
+                && layout.getHeight() > height)
+            || (text.length() == 1 && layout.getPaint().measureText(text.toString()) > width))) {
       // TODO: We could probably use a smarter algorithm here. This will require 0(n)
       // measurements based on the number of points the font size needs to be reduced by.
       currentFontSize -= Math.max(1, (int) PixelUtil.toPixelFromDIP(1));
@@ -648,6 +649,7 @@ private static Layout createLayout(
             text.getSpanFlags(span));
         text.removeSpan(span);
       }
+      boring = BoringLayout.isBoring(text, paint);
       layout =
           createLayout(
               text,