Changed successPercentage rounding function

Changed from Math.round to Math.floor
Added tests to cover percentage rounding

app/assets/javascripts/pipelines/components/test_reports/test_summary.vue

@@ -28,7 +28,9 @@ export default {
       return this.report.name || __('Summary');
     },
     successPercentage() {
-      return Math.round((this.report.success_count / this.report.total_count) * 100) || 0;
+      // Returns a full number when the decimals equal .00.
+      // Otherwise returns a float to two decimal points
+      return Number(((this.report.success_count / this.report.total_count) * 100 || 0).toFixed(2));
     },
     formattedDuration() {
       return formatTime(secondsToMilliseconds(this.report.total_time));

changelogs/unreleased/37363-junit-xml-summary-incorrectly-shows-100-success-rate.yml

+---
+title: Junit success percentage no longer displays 100% if there are failures
+merge_request: 20835
+author:
+type: fixed

spec/frontend/pipelines/test_reports/test_summary_spec.js

@@ -79,4 +79,25 @@ describe('Test reports summary', () => {
       expect(duration().text()).toBe('00:00:00');
     });
   });
+
+  describe('success percentage calculation', () => {
+    it.each`
+      name                                     | successCount | totalCount | result
+      ${'displays 0 when there are no tests'}  | ${0}         | ${0}       | ${'0'}
+      ${'displays whole number when possible'} | ${10}        | ${50}      | ${'20'}
+      ${'rounds to 0.01'}                      | ${1}         | ${16604}   | ${'0.01'}
+      ${'correctly rounds to 50'}              | ${8302}      | ${16604}   | ${'50'}
+      ${'rounds down for large close numbers'} | ${16603}     | ${16604}   | ${'99.99'}
+      ${'correctly displays 100'}              | ${16604}     | ${16604}   | ${'100'}
+    `('$name', ({ successCount, totalCount, result }) => {
+      createComponent({
+        report: {
+          success_count: successCount,
+          total_count: totalCount,
+        },
+      });
+
+      expect(successRate().text()).toBe(`${result}% success rate`);
+    });
+  });
 });