tests(i18n): direct test for _byteFormatterForGranularity

GoogleChrome · Sep 30, 2020 · f03d5e3 · f03d5e3
1 parent c534d3d
commit f03d5e3
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Showing 2 changed files with 31 additions and 3 deletions.
diff --git a/lighthouse-core/report/html/renderer/i18n.js b/lighthouse-core/report/html/renderer/i18n.js
@@ -67,10 +67,11 @@ class I18n {
    * @return {Intl.NumberFormat}
    */
   _byteFormatterForGranularity(granularity) {
-    if (granularity >= 1) {
-      return this._numberFormatter;
+    let numberOfFractionDigits = 0;
+    if (granularity < 1) {
+      // assumes granularities above 1 will not contain fractional parts, i.e. will never be 1.5
+      numberOfFractionDigits = -Math.floor(Math.log10(granularity));
     }
-    const numberOfFractionDigits = -Math.floor(Math.log10(granularity));
     return new Intl.NumberFormat(this._numberDateLocale, {
       maximumFractionDigits: numberOfFractionDigits,
       minimumFractionDigits: numberOfFractionDigits,

diff --git a/lighthouse-core/test/report/html/renderer/i18n-test.js b/lighthouse-core/test/report/html/renderer/i18n-test.js
@@ -89,4 +89,31 @@ describe('util helpers', () => {
       timestamp.includes('Apr 29, 2017')
     );
   });
+
+  describe('_byteFormatterForGranularity', () => {
+    it('returns a formatter that outputs a consistent number of fractional digits', () => {
+      const i18n = new I18n('en', {...Util.UIStrings});
+
+      const formatterTen = i18n._byteFormatterForGranularity(10);
+      const formatterOne = i18n._byteFormatterForGranularity(1);
+      const formatterHalf = i18n._byteFormatterForGranularity(0.5);
+      const formatterTenth = i18n._byteFormatterForGranularity(0.1);
+      const formatterHundredth = i18n._byteFormatterForGranularity(0.01);
+
+      assert.strictEqual(formatterTen.format(15.0), '15');
+      assert.strictEqual(formatterTen.format(15.12345), '15');
+
+      assert.strictEqual(formatterOne.format(15.0), '15');
+      assert.strictEqual(formatterOne.format(15.12345), '15');
+
+      assert.strictEqual(formatterHalf.format(15.0), '15.0');
+      assert.strictEqual(formatterHalf.format(15.12345), '15.1');
+
+      assert.strictEqual(formatterTenth.format(15.0), '15.0');
+      assert.strictEqual(formatterTenth.format(15.12345), '15.1');
+
+      assert.strictEqual(formatterHundredth.format(15.0), '15.00');
+      assert.strictEqual(formatterHundredth.format(15.12345), '15.12');
+    });
+  });
 });