adds a snapshot test

Author: madkate42

test/fixtures/test-runner/output/dot_reporter_coverage.mjs

@@ -0,0 +1,13 @@
+// Flags: --experimental-test-coverage --test-coverage-lines=99
+// here we can't import common module as the coverage will be different based on the system
+// Unused imports are here in order to populate the coverage report
+// eslint-disable-next-line no-unused-vars
+import * as a from '../coverage-snap/b.js';
+// eslint-disable-next-line no-unused-vars
+import * as b from '../coverage-snap/a.js';
+
+import { test } from 'node:test';
+
+process.stdout.columns = 80;
+
+test('passing test for dot coverage report');

test/fixtures/test-runner/output/dot_reporter_coverage.snapshot

@@ -0,0 +1,19 @@
+.
+
+ℹ Error: *% line coverage does not meet threshold of 99%.
+ℹ start of coverage report
+ℹ ------------------------------------------------------------------------------
+ℹ file                      | line % | branch % | funcs % | uncovered lines
+ℹ ------------------------------------------------------------------------------
+ℹ test                      |        |          |         |
+ℹ  fixtures                 |        |          |         |
+ℹ   test-runner             |        |          |         |
+ℹ    coverage-snap          |        |          |         |
+ℹ     a.js                  |  55.77 |   100.00 |    0.00 | 5-7 9-11 13-15 17-…
+ℹ     b.js                  |  45.45 |   100.00 |    0.00 | 5-7 9-11
+ℹ    output                 |        |          |         |
+ℹ     dot_reporter_cove….mjs | 100.00 |   100.00 |  100.00 |
+ℹ ------------------------------------------------------------------------------
+ℹ all files                 |  61.84 |   100.00 |    0.00 |
+ℹ ------------------------------------------------------------------------------
+ℹ end of coverage report

test/test-runner/test-output-dot-reporter-coverage.mjs

@@ -0,0 +1,16 @@
+// Test that the output of test-runner/output/dot_reporter_coverage.mjs matches
+// test-runner/output/dot_reporter_coverage.snapshot
+import * as common from '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import { spawnAndAssert, defaultTransform, ensureCwdIsProjectRoot } from '../common/assertSnapshot.js';
+
+if (!process.features.inspector) {
+  common.skip('inspector support required');
+}
+
+ensureCwdIsProjectRoot();
+await spawnAndAssert(
+  fixtures.path('test-runner/output/dot_reporter_coverage.mjs'),
+  defaultTransform,
+  { flags: ['--test-reporter=dot', '--test-coverage-exclude=!test/**'] },
+);