test: Migrate to Jest (#1596)

Jest has the same minimum Node version as Mocha, but comes with a lot of batteries included (eg. coverage, assertions), which helps with making things more predictable.

Most of these changes were made using `jest-codemods`.

.gitignore

@@ -1,5 +1,5 @@
 node_modules
 npm-debug.log
 .DS_Store
-.nyc_output
+/coverage
 /docs/out/

.prettierignore

@@ -1,3 +1,3 @@
 node_modules
-.nyc_output
+/coverage
 docs

Makefile

@@ -18,12 +18,12 @@ subl:
 	@subl lib/ test/ package.json index.js
 
 test-cov:
-	@./node_modules/.bin/nyc node_modules/.bin/_mocha -- --recursive --reporter $(REPORTER)
+	@./node_modules/.bin/jest --coverage
 
 # Due to occasional unavailability of the code coverage reporting service, the
 # exit status of the command in this recipe may optionally be ignored.
 report-cov: test-cov
-	@./node_modules/.bin/nyc report --reporter=text-lcov | ./node_modules/.bin/coveralls || [ "$(OPTIONAL)" = "true" ]
+	cat coverage/lcov.info | ./node_modules/.bin/coveralls || [ "$(OPTIONAL)" = "true" ]
 
 travis-test: OPTIONAL = true
 travis-test: lint types report-cov

lib/api/manipulation.js

@@ -246,11 +246,11 @@ function _wrap(insert) {
       // (ignore text); stop if no children are found.
       var j = 0;
 
-      while (elInsertLocation && elInsertLocation.children) {
-        if (j >= elInsertLocation.children.length) {
-          break;
-        }
-
+      while (
+        elInsertLocation &&
+        elInsertLocation.children &&
+        j < elInsertLocation.children.length
+      ) {
         if (elInsertLocation.children[j].type === 'tag') {
           elInsertLocation = elInsertLocation.children[j];
           j = 0;
@@ -425,7 +425,7 @@ exports.wrapAll = function (wrapper) {
     while (
       elInsertLocation &&
       elInsertLocation.children &&
-      j >= elInsertLocation.children.length
+      j < elInsertLocation.children.length
     ) {
       if (elInsertLocation.children[j].type === 'tag') {
         elInsertLocation = elInsertLocation.children[j];