Fixing line diff bug and code folding bug

Author: praneshr

src/compute-lines.ts

@@ -132,14 +132,16 @@ const computeLineInformation = (
     diffIndex: number,
     added?: boolean,
     removed?: boolean,
+    evaluateOnlyFirstLine?: boolean,
   ): LineInformation[] => {
     const lines = constructLines(value);
 
     return lines.map((line: string, lineIndex): LineInformation => {
       const left: DiffInformation = {};
       const right: DiffInformation = {};
-      if (ignoreDiffIndexes.includes(`${diffIndex}-${lineIndex}`)) {
-        return { left: {}, right: {}};
+      if (ignoreDiffIndexes.includes(`${diffIndex}-${lineIndex}`)
+        || (evaluateOnlyFirstLine && lineIndex !== 0)) {
+        return undefined;
       }
       if (added || removed) {
         if (!diffLines.includes(counter)) {
@@ -162,7 +164,7 @@ const computeLineInformation = (
                 value: rightValue,
                 lineNumber,
                 type,
-              } = getLineInformation(nextDiff.value, diffIndex, true)[lineIndex].right;
+              } = getLineInformation(nextDiff.value, diffIndex, true, false, true)[0].right;
               // When identified as modification, push the next diff to ignore
               // list as the next value will be added in this line computation as
               // right and left values.
@@ -200,7 +202,7 @@ const computeLineInformation = (
 
       counter += 1;
       return { right, left };
-    });
+    }).filter(Boolean);
   };
 
   diffArray

src/index.tsx

@@ -462,7 +462,7 @@ class DiffViewer extends React.Component<ReactDiffViewerProps, ReactDiffViewerSt
           ? this.renderSplitView(line, i)
           : this.renderInlineView(line, i);
 
-        if (currentPosition === extraLines && skippedLines.length > 1) {
+        if (currentPosition === extraLines && skippedLines.length > 0) {
           const { length } = skippedLines;
           skippedLines = [];
           return (

test/react-diff-viewer-test.tsx

@@ -39,7 +39,7 @@ describe('Testing react diff viewer', (): void => {
       newValue={newCode}
     />);
 
-    expect(node.find('table > tbody tr').length).toEqual(6);
+    expect(node.find('table > tbody tr').length).toEqual(7);
   });
 
   it('It should render diff lines in inline view', (): void => {