tests(jest): helper file

Author: sam bacha

tests_config/helpers.js

@@ -0,0 +1,45 @@
+// @file jest helper file
+const fs = require('fs');
+const path = require('path');
+const prettier = require('prettier');
+
+function mergeDefaultOptions(parserConfig) {
+  return {
+    plugins: [path.dirname(__dirname)],
+    printWidth: 80,
+    ...parserConfig
+  };
+}
+
+function prettyprint(src, options) {
+  const result = prettier.formatWithCursor(src, options);
+  if (options.cursorOffset >= 0) {
+    result.formatted = `${result.formatted.slice(
+      0,
+      result.cursorOffset
+    )}<|>${result.formatted.slice(result.cursorOffset)}`;
+  }
+  return result.formatted;
+}
+
+/**
+ * Wraps a string in a marker object that is used by `./raw-serializer.js` to
+ * directly print that string in a snapshot without escaping all double quotes.
+ * Backticks will still be escaped.
+ */
+function raw(string) {
+  if (typeof string !== 'string') {
+    throw new Error('Raw snapshots have to be strings.');
+  }
+  return { [Symbol.for('raw')]: string };
+}
+
+function read(filename) {
+  return fs.readFileSync(filename, 'utf8');
+}
+
+function parse(string, opts) {
+  return prettier.__debug.parse(string, opts, /* massage */ true).ast;
+}
+
+module.exports = { mergeDefaultOptions, parse, prettyprint, raw, read };