Put all the sorting related bits close to each other

src/dashboard.ts

@@ -499,14 +499,10 @@ export async function calculateAllStatisticsAndRenderPlots(
   change: string,
   reportId: string
 ): Promise<StatsSummary> {
-  const cmp = base.localeCompare(change);
-  if (cmp === 0) {
-    throw new Error('base and change are the same');
-  }
-  const baseCommitIdIsFirst = cmp < 0;
-
-  const baseOffset = baseCommitIdIsFirst ? 0 : 1;
-  const changeOffset = baseCommitIdIsFirst ? 1 : 0;
+  const { baseOffset, changeOffset } = getCommitOffsetsInSortedMeasurements(
+    base,
+    change
+  );
 
   const criteria = new Map<string, ComparisonStatistics[]>();
 

src/stats-data-prep.ts

@@ -75,6 +75,22 @@ export function compareToSortForSinglePassChangeStatsWithoutCommitId(
   return a.criterion.name.localeCompare(b.criterion.name);
 }
 
+export function getCommitOffsetsInSortedMeasurements(
+  baseCommitId: string,
+  changeCommitId: string
+): { baseOffset: number; changeOffset: number } {
+  const cmp = baseCommitId.localeCompare(changeCommitId);
+  if (cmp === 0) {
+    throw new Error('base and change are the same');
+  }
+  const baseCommitIdIsFirst = cmp < 0;
+
+  return {
+    baseOffset: baseCommitIdIsFirst ? 0 : 1,
+    changeOffset: baseCommitIdIsFirst ? 1 : 0
+  };
+}
+
 export interface ResultsByBenchmark {
   benchmarks: Map<string, ProcessedResult>;
   criteria: Record<string, CriterionData>;