Add option to pad ratchet percentages

src/index.ts

@@ -50,7 +50,7 @@ function onRunComplete(globalConfig: Config, options: RatchetOptions) {
       const coverageRaw = readFileSync(coverageSummaryPath, 'utf-8');
       const summary: IstanbulCoverage = JSON.parse(coverageRaw);
       const threshold = globalConfig.coverageThreshold!;
-      const ratchetResult = ratchetCoverage(threshold, summary);
+      const ratchetResult = ratchetCoverage(threshold, summary, options);
 
       updateFile(jestConfigPath, ratchetResult);
     });

src/interfaces.ts

@@ -33,8 +33,8 @@ export interface JestCoverageCategory {
 }
 
 export interface RatchetOptions {
-  disable?: boolean;
-  stop?: JestCoverage;
+  /** Pad the ratchet percentage by a specified number. */
+  ratchetPercentagePadding?: number;
 }
 
 export interface Config {

src/ratchet.ts

@@ -4,39 +4,47 @@ import {
   IstanbulCoverageCategory,
   JestCoverage,
   JestCoverageCategory,
+  RatchetOptions,
 } from './interfaces';
 
 export function ratchetCoverage(
   threshold: JestCoverage,
   summary: IstanbulCoverage,
+  options: RatchetOptions,
 ): JestCoverage {
   const result: any = {};
   for (const key of Object.keys(threshold)) {
     const summaryKey = key === 'global' ? 'total' : key;
-    result[key] = ratchetSingleCoverage(threshold[key], summary[summaryKey]);
+    result[key] = ratchetSingleCoverage(threshold[key], summary[summaryKey], options);
   }
   return result;
 }
 
 function ratchetSingleCoverage(
   threshold: JestCoverageCategory,
   summary: IstanbulCoverageCategories,
+  options: RatchetOptions,
 ) {
   const { branches, functions, lines, statements } = threshold;
   return {
-    branches: ratchetSingleNumberCoverage(branches, summary.branches),
-    functions: ratchetSingleNumberCoverage(functions, summary.functions),
-    lines: ratchetSingleNumberCoverage(lines, summary.lines),
-    statements: ratchetSingleNumberCoverage(statements, summary.statements),
+    branches: ratchetSingleNumberCoverage(branches, summary.branches, options),
+    functions: ratchetSingleNumberCoverage(functions, summary.functions, options),
+    lines: ratchetSingleNumberCoverage(lines, summary.lines, options),
+    statements: ratchetSingleNumberCoverage(statements, summary.statements, options),
   };
 }
 
 function ratchetSingleNumberCoverage(
   num: number | undefined,
   category: IstanbulCoverageCategory,
+  options: RatchetOptions,
 ) {
   if (num && category && num > 0 && num <= category.pct) {
-    return category.pct;
+    if (options.ratchetPercentagePadding) {
+      return Math.round(category.pct) - options.ratchetPercentagePadding;
+    } else {
+      return category.pct;
+    }
   } else if (num && category && num < 0 && num >= -category.covered) {
     return -category.covered;
   }