[#21] Added a missing test

Author: ryu1kn

src/lib/field-stringifier.ts

@@ -15,13 +15,21 @@ export abstract class FieldStringifier {
     }
 
     abstract stringify(value?: Field): string;
+
+    protected isEmpty(value?: Field): boolean {
+        return typeof value === 'undefined' || value === null || value === '';
+    }
+
+    protected quoteField(field: string): string {
+        return `"${field.replace(/"/g, '""')}"`;
+    }
 }
 
 class DefaultFieldStringifier extends FieldStringifier {
     stringify(value?: Field): string {
-        if (typeof value === 'undefined' || value === null) return '';
+        if (this.isEmpty(value)) return '';
         const str = String(value);
-        return this.needsQuote(str) ? `"${str.replace(/"/g, '""')}"` : str;
+        return this.needsQuote(str) ? this.quoteField(str) : str;
     }
 
     private needsQuote(str: string): boolean {
@@ -31,9 +39,7 @@ class DefaultFieldStringifier extends FieldStringifier {
 
 class ForceQuoteFieldStringifier extends FieldStringifier {
     stringify(value?: Field): string {
-        if (typeof value === 'undefined' || value === null) return '';
-        const str = String(value);
-        return `"${str.replace(/"/g, '""')}"`;
+        return this.isEmpty(value) ? '' : this.quoteField(String(value));
     }
 }
 

src/test/field-stringifier.test.ts

@@ -8,6 +8,26 @@ describe('DefaultFieldStringifier', () => {
 
     describe('When field delimiter is semicolon', generateTestCases(';'));
 
+    describe('When all fields needs to be quoted', () => {
+        const stringifier = createFieldStringifier(',', true);
+
+        it('quotes a field', () => {
+            strictEqual(stringifier.stringify('VALUE'), '"VALUE"');
+        });
+
+        it('does not quote a field of value undefined', () => {
+            strictEqual(stringifier.stringify(), '');
+        });
+
+        it('does not quote a field of value null', () => {
+            strictEqual(stringifier.stringify(null), '');
+        });
+
+        it('does not quote a field of value empty string', () => {
+            strictEqual(stringifier.stringify(''), '');
+        });
+    });
+
     function generateTestCases(fieldDelimiter: string) {
         const delim = resolveDelimiterChar(fieldDelimiter);
         return () => {