fix: stringify coverage object to improve performance (#98)

Author: bahmutov

support.js

@@ -23,7 +23,7 @@ if (Cypress.env('coverage') === false) {
  const applicationSourceCoverage = win.__coverage__
 
  if (applicationSourceCoverage) {
- cy.task('combineCoverage', applicationSourceCoverage)
+ cy.task('combineCoverage', JSON.stringify(applicationSourceCoverage))
  }
  })
  })
@@ -54,7 +54,7 @@ if (Cypress.env('coverage') === false) {
  // original failed request
  return
  }
- cy.task('combineCoverage', coverage)
+ cy.task('combineCoverage', JSON.stringify(coverage))
  })
  }
 
@@ -75,7 +75,7 @@ if (Cypress.env('coverage') === false) {
  (fileCoverage, filename) =>
  filename.startsWith(specFolder) || filename.startsWith(supportFolder)
  )
- cy.task('combineCoverage', coverage)
+ cy.task('combineCoverage', JSON.stringify(coverage))
  }
 
  // when all tests finish, lets generate the coverage report

task.js

@@ -61,8 +61,14 @@ module.exports = {
  /**
  * Combines coverage information from single test
  * with previously collected coverage.
+ *
+ * @param {string} sentCoverage Stringified coverage object sent by the test runner
+ * @returns {null} Nothing is returned from this task
  */
- combineCoverage(coverage) {
+ combineCoverage(sentCoverage) {
+ const coverage = JSON.parse(sentCoverage)
+ debug('parsed sent coverage')
+
  fixSourcePathes(coverage)
  const previous = existsSync(nycFilename)
  ? JSON.parse(readFileSync(nycFilename))