Fix string methods to handle empty values (#4442)

* Enable strings category methods tests

* Ensure escape, pad, padEnd, padStart, trim, trimEnd, trimStart, unescape return an empty string for falsey values

* Coerce value to string using toString in truncate, capitalize and case methods

* Ensure createCaseFirst returns an empty string for falsey values

test/Strings-category-methods.js

@@ -1,43 +0,0 @@
-import assert from 'assert';
-import lodashStable from 'lodash';
-import { _, stubString } from './utils.js';
-
-describe('"Strings" category methods', function() {
-  var stringMethods = [
-    'camelCase',
-    'capitalize',
-    'escape',
-    'kebabCase',
-    'lowerCase',
-    'lowerFirst',
-    'pad',
-    'padEnd',
-    'padStart',
-    'repeat',
-    'snakeCase',
-    'toLower',
-    'toUpper',
-    'trim',
-    'trimEnd',
-    'trimStart',
-    'truncate',
-    'unescape',
-    'upperCase',
-    'upperFirst'
-  ];
-
-  lodashStable.each(stringMethods, function(methodName) {
-    var func = _[methodName];
-
-    it('`_.' + methodName + '` should return an empty string for empty values', function() {
-      var values = [, null, undefined, ''],
-          expected = lodashStable.map(values, stubString);
-
-      var actual = lodashStable.map(values, function(value, index) {
-        return index ? func(value) : func();
-      });
-
-      assert.deepStrictEqual(actual, expected);
-    });
-  });
-});

test/Strings-category-methods.test.js

@@ -0,0 +1,83 @@
+import assert from 'assert';
+import lodashStable from 'lodash';
+import { stubString } from './utils.js';
+
+import camelCase from '../camelCase.js';
+import capitalize from '../capitalize.js';
+import escape from '../escape.js';
+import kebabCase from '../kebabCase.js';
+import lowerCase from '../lowerCase.js';
+import lowerFirst from '../lowerFirst.js';
+import pad from '../pad.js';
+import padEnd from '../padEnd.js';
+import padStart from '../padStart.js';
+import repeat from '../repeat.js';
+import snakeCase from '../snakeCase.js';
+import trim from '../trim.js';
+import trimStart from '../trimStart.js';
+import trimEnd from '../trimEnd.js';
+import truncate from '../truncate.js';
+import unescape from '../unescape.js';
+import upperCase from '../upperCase.js';
+import upperFirst from '../upperFirst';
+
+
+const methods = {
+  camelCase,
+  capitalize,
+  escape,
+  kebabCase,
+  lowerCase,
+  lowerFirst,
+  pad,
+  padEnd,
+  padStart,
+  repeat,
+  snakeCase,
+  trim,
+  trimStart,
+  trimEnd,
+  truncate,
+  unescape,
+  upperCase,
+  upperFirst
+}
+
+
+describe('"Strings" category methods', function() {
+  var stringMethods = [
+    'camelCase',
+    'capitalize',
+    'escape',
+    'kebabCase',
+    'lowerCase',
+    'lowerFirst',
+    'pad',
+    'padEnd',
+    'padStart',
+    'repeat',
+    'snakeCase',    
+    'trim',
+    'trimEnd',
+    'trimStart',
+    'truncate',
+    'unescape',
+    'upperCase',
+    'upperFirst'
+  ];
+
+  lodashStable.each(stringMethods, function(methodName) {
+    var func = methods[methodName];
+
+    it('`_.' + methodName + '` should return an empty string for empty values', function() {
+      var values = [, null, undefined, ''],
+          expected = lodashStable.map(values, stubString);
+
+      var actual = lodashStable.map(values, function(value, index) {
+        return index ? func(value) : func();
+      });
+
+      assert.deepStrictEqual(actual, expected);
+    });
+  });
+});