add threshold-uncovered option

allows threshold to be set by number of uncovered lines instead of percentage
of coverage.

In a codebase which continuously grows, if you fix the number of lines uncovered
then you (loosely) enforce that all new code should be covered.

closes #168

Author: guyfedwards

package.json

@@ -15,6 +15,7 @@
   "scripts": {
     "ava": "nyc ava --verbose",
     "build": "rimraf dist && babel -d dist src --only src/lib --source-maps",
+    "dev": "babel -d dist src --only src/lib --source-maps --watch",
     "update-flow-typed": "rimraf flow-typed && flow-typed install -s -i dev",
     "flow-coverage": "bin/flow-coverage-report.js",
     "flow-check": "flow check",

src/__tests__/fixtures.js

@@ -33,6 +33,7 @@ const FLOW_COVERAGE_SUMMARY_DATA = {
   covered_count: 5,
   uncovered_count: 5,
   threshold: 40,
+  uncoveredThreshold: 3,
   percent: 50,
   globIncludePatterns: [firstGlob, secondGlob],
   files: allFiles.reduce((acc, filename) => {

src/__tests__/react-components/__snapshots__/test-coverage-meter-bar.js.snap

@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`<FlowCoverageMeterBar /> 1`] = `
+exports[`<FlowCoverageMeterBar /> percent <= threshold 1`] = `
 <div
   className="row red"
   style={
@@ -11,3 +11,15 @@ exports[`<FlowCoverageMeterBar /> 1`] = `
   }
 />
 `;
+
+exports[`<FlowCoverageMeterBar /> uncoveredCount <= thresholdUncovered 1`] = `
+<div
+  className="row green"
+  style={
+    Object {
+      "height": 12,
+      "padding": 0,
+    }
+  }
+/>
+`;

src/__tests__/react-components/__snapshots__/test-coverage-summary-table.js.snap

@@ -83,3 +83,45 @@ exports[`<FlowCoverageSummaryTable /> 2`] = `
   </tbody>
 </table>
 `;
+
+exports[`<FlowCoverageSummaryTable /> 3`] = `
+<table
+  className="ui small celled table"
+>
+  <thead>
+    <tr>
+      <th>
+        Percent
+      </th>
+      <th>
+        Total
+      </th>
+      <th>
+        Covered
+      </th>
+      <th>
+        Uncovered
+      </th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr
+      className="positive"
+    >
+      <td>
+        50
+         %
+      </td>
+      <td>
+        10
+      </td>
+      <td>
+        5
+      </td>
+      <td>
+        5
+      </td>
+    </tr>
+  </tbody>
+</table>
+`;

src/__tests__/react-components/test-coverage-meter-bar.js

@@ -9,14 +9,26 @@ import {BASE_DIR} from './common';
 
 const REACT_COMPONENT = `${BASE_DIR}/coverage-meter-bar`;
 
-test('<FlowCoverageMeterBar />', () => {
-  const FlowCoverageMeterBar = require(REACT_COMPONENT).default;
-  const props = {
-    percent: 20,
-    threshold: 80
-  };
-  const tree = renderer.create(<FlowCoverageMeterBar {...props}/>).toJSON();
-  expect(tree).toMatchSnapshot();
+describe('<FlowCoverageMeterBar />', () => {
+  test('percent <= threshold', () => {
+    const FlowCoverageMeterBar = require(REACT_COMPONENT).default;
+    const props = {
+      percent: 20,
+      threshold: 80
+    };
+    const tree = renderer.create(<FlowCoverageMeterBar {...props}/>).toJSON();
+    expect(tree).toMatchSnapshot();
+  });
+
+  test('uncoveredCount <= thresholdUncovered', () => {
+    const FlowCoverageMeterBar = require(REACT_COMPONENT).default;
+    const props = {
+      uncoveredCount: 20,
+      thresholdUncovered: 30
+    };
+    const tree = renderer.create(<FlowCoverageMeterBar {...props}/>).toJSON();
+    expect(tree).toMatchSnapshot();
+  });
 });
 
 test.skip('<FlowCoverageMeterBar /> with missing props');

src/__tests__/react-components/test-coverage-summary-table.js

@@ -21,12 +21,19 @@ test('<FlowCoverageSummaryTable />', () => {
   const positiveSummaryTree = renderer.create(<FlowCoverageSummaryTable {...positiveSummaryProps}/>).toJSON();
   expect(positiveSummaryTree).toMatchSnapshot();
 
-  // Expect positive with higher threshold.
+  // Expect negative with higher threshold.
   const negativeSummaryProps = {
     coverageSummaryData: {...FLOW_COVERAGE_SUMMARY_DATA, threshold: 90}
   };
   const negativeSummaryTree = renderer.create(<FlowCoverageSummaryTable {...negativeSummaryProps}/>).toJSON();
   expect(negativeSummaryTree).toMatchSnapshot();
+
+  // Expect negative with uncovered_count >= thresholdUncovered
+  const negativeSummaryUncoveredProps = {
+    coverageSummaryData: {...FLOW_COVERAGE_SUMMARY_DATA, uncoveredThreshold: 4}
+  };
+  const negativeSummaryUncoveredTree = renderer.create(<FlowCoverageSummaryTable {...negativeSummaryUncoveredProps}/>).toJSON();
+  expect(negativeSummaryUncoveredTree).toMatchSnapshot();
 });
 
 test.skip('<FlowCoverageSummaryTable /> with missing props');

src/__tests__/test-flow.js

@@ -430,6 +430,7 @@ const testCollectFlowCoverage = async ({
     globIncludePatterns,
     globExcludePatterns,
     threshold: 80,
+    thresholdUncovered: 3,
     concurrentFiles: 5,
     strictCoverage,
     excludeNonFlow
@@ -462,6 +463,7 @@ const testCollectFlowCoverage = async ({
     concurrentFiles: 5,
     percent: 50,
     threshold: 80,
+    thresholdUncovered: 3,
     /* eslint-disable camelcase */
     covered_count: excludeNonFlow ? 4 : 5,
     uncovered_count: excludeNonFlow ? 4 : 5,

src/__tests__/test-index.js

@@ -116,4 +116,14 @@ it('generateFlowCoverageReport', async () => {
   expect(exception3 && exception3.message).toMatch(
     /empty globIncludePatterns option/
   );
+
+  let exception4;
+  try {
+    await generateFlowCoverageReport({...options, threshold: undefined, thresholdUncovered: undefined});
+  } catch (err) {
+    exception4 = err;
+  }
+  expect(exception4 && exception4.message).toMatch(
+    /threshold or thresholdUncovered option is mandatory/
+  );
 });

src/lib/cli/args.js

@@ -73,6 +73,10 @@ export default function processArgv(argv: Array<string>): any {
       type: 'number',
       describe: `the minimum coverage percent requested (defaults to ${defaultConfig.threshold})`
     })
+    .options('threshold-uncovered', {
+      type: 'number',
+      describe: `the maximum number of uncovered lines`
+    })
     .options('percent-decimals', {
       alias: ['percentDecimanls'],
       type: 'number',

src/lib/cli/config.js

@@ -19,6 +19,7 @@ export type ConfigParams = {|
   globExcludePatterns?: Array<string>,
   globIncludePatterns: Array<string>,
   threshold: number,
+  thresholdUncovered: number,
   percentDecimals: number,
   outputDir: string,
   concurrentFiles?: number,
@@ -58,11 +59,12 @@ export const defaultConfig: DefaultConfigParams = {
   projectDir: path.resolve(process.cwd()),
   globExcludePatterns: ['node_modules/**'],
   globIncludePatterns: [],
-  threshold: 80,
   percentDecimals: 0,
   outputDir: './flow-coverage',
   concurrentFiles: 1,
   strictCoverage: false,
+  threshold: 80,
+  thresholdUncovered: 0,
   excludeNonFlow: false,
   noConfig: false,
   htmlTemplateOptions: {