Fixed 31 / 3 failure in Calculator default app.

A problem with the rounding logic was causing any operation whose result
was a decimal larger than 10 with more than 7 digits after the decimal
to fail. (31 / 3) is one such operation. This was fixed and a test was
added for this case. Comments were also added to the tests to describing
some other test cases that need to be tested for and/or fixed. The
simplest fix to the rounding problem involved adding support for the
display of exponential values, which will probably fix a couple of
aspects of http://crbug/156453.

BUG=156448
BUG=156453


Review URL: https://chromiumcodereview.appspot.com/11183051

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@163504 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 108 insertions, 9 deletions

diff --git a/chrome/common/extensions/docs/examples/apps/calculator/app/model.js b/chrome/common/extensions/docs/examples/apps/calculator/app/model.js
index 295a297..ba7a258 100644
--- a/chrome/common/extensions/docs/examples/apps/calculator/app/model.js
+++ b/chrome/common/extensions/docs/examples/apps/calculator/app/model.js
@@ -111,12 +111,32 @@ Model.prototype.calculate_ = function(operator, operand) {
 
 /**
  * Returns the string representation of the passed in value rounded to the
- * model's precision, or "+Infinity" or "-Infinity" on overflow.
+ * model's precision, or "E" on overflow.
  *
  * @private
  */
 Model.prototype.round_ = function(x) {
-  var rounded = String(Number(x.toFixed(this.precision - 1)));
-  var overflow = (rounded.replace(/[^0-9]/g, '').length > this.precision);
-  return (overflow || Math.abs(x) == Infinity) ? 'E' : rounded;
+  var exponent = Number(x.toExponential(this.precision - 1).split('e')[1]);
+  var digits = this.digits_(exponent);
+  var exponential = x.toExponential(digits).replace(/\.?0+e/, 'e');
+  var fixed = (Math.abs(exponent) < this.precision && exponent > -7);
+  return !digits ? 'E' : fixed ? String(Number(exponential)) : exponential;
+}
+
+/**
+ * Returns the appropriate number of digits to include of a number based on
+ * its size.
+ *
+ * @private
+ */
+Model.prototype.digits_ = function(exponent) {
+  return (isNaN(exponent) || exponent < -199 || exponent > 199) ? 0 :
+         (exponent < -99) ? (this.precision - 1 - 5) :
+         (exponent < -9) ? (this.precision - 1 - 4) :
+         (exponent < -6) ? (this.precision - 1 - 3) :
+         (exponent < 0) ? (this.precision - 1 + exponent) :
+         (exponent < this.precision) ? (this.precision - 1) :
+         (exponent < 10) ? (this.precision - 1 - 3) :
+         (exponent < 100) ? (this.precision - 1 - 4) :
+                            (this.precision - 1 - 5);
 }
diff --git a/chrome/common/extensions/docs/examples/apps/calculator/tests/model_tests.js b/chrome/common/extensions/docs/examples/apps/calculator/tests/model_tests.js
index b52fe19..1b447ed 100644
--- a/chrome/common/extensions/docs/examples/apps/calculator/tests/model_tests.js
+++ b/chrome/common/extensions/docs/examples/apps/calculator/tests/model_tests.js
@@ -10,11 +10,90 @@
 window.runTests = function(log) {
   var run = window.calculatorTestRun.create();
 
-  // TODO(dharcourt@chromium.org): Organize and beef up these tests.
-  // TODO(dharcourt@chromium.org): test.run("*", '~ = [-0]');
-  // TODO(dharcourt@chromium.org): test.run("*", '~42 [[-42]]');
-  // TODO(dharcourt@chromium.org): test.run("*", '1 / 3 * 3 = [[1]]');
-  // TODO(dharcourt@chromium.org): Test {nega,posi}tive {under,over}flows.
+  // ---------------------------------------------------------------------------
+  // Test fixes for <http://crbug.com/156448>:
+
+  run.test('Twenty eight can be divided by three', '28 / 3 = [9.33333333]');
+  run.test('Twenty nine can be divided by three', '29 / 3 = [9.66666667]');
+  run.test('Thirty can be divided by three', '30 / 3 = [10]');
+  run.test('Thirty one can be divided by three', '31 / 3 = [10.3333333]');
+  run.test('Thirty two can be divided by three', '32 / 3 = [10.6666667]');
+  run.test('Thirty three can be divided by three', '33 / 3 = [11]');
+
+  // ---------------------------------------------------------------------------
+  // Test fixes for <http://crbug.com/156449>:
+
+  // run.test('Equals without operator results in operand value',
+  //          '123 = [123]');
+
+  // TODO(dharcourt): Test the display for the expected output.
+  // run.test('Successive operators replace each other.',
+  //          '123 + - * / [123 / null] and no previous [* + *]');
+
+  // ---------------------------------------------------------------------------
+  // Test fixes for <http://crbug.com/156450>:
+
+  // run.test('Operand can be erased and replaced',
+  //          '123 + 456 < < < < 789 = [789]');
+
+  // TODO(dharcourt): Test the display for the expected output.
+  // run.test('Erase is ignored after equals.', '123 + 456 = < [579]');
+  // run.test('Erase is ignored after zero result.', '123 - 123 = < [9]');
+
+  // TODO(dharcourt): Test the display for the expected output.
+  // run.test('Erasing an operand makes it blank.',
+  //          '123 + 456 < < < [null + null]');
+
+  // ---------------------------------------------------------------------------
+  // Test fixes for <http://crbug.com/156451>:
+
+  // run.test('Negation applies to zero', '~ [[-0]]');
+  // run.test('Negation applies before input', '~ 123 = [[-123]]');
+  // run.test('Negation applies after input is erased',
+  //          '123 < < < ~ 456 [[-456]]');
+  // run.test('Negation is preserved when input is erased',
+  //          '123 ~ < < < 456 [[-456]]');
+  // run.test('Negation supports small values',
+  //          '0.0000001 ~ [[-0.0000001]]');
+
+  // run.test('Addition resets negated zeros', '~ + [null + [0]]');
+  // run.test('Subtraction resets negated zeros', '~ - [null - [0]]');
+  // run.test('Multiplication resets negated zeros', '~ * [null * [0]]');
+  // run.test('Division resets negated zeros', '~ / [null / [0]]');
+  // run.test('Equals resets negated zeros', '~ = [0 null [0]]');
+
+  // ---------------------------------------------------------------------------
+  // Test fixes for <http://crbug.com/156452>:
+
+  // TODO(dharcourt): Test the display for the expected output.
+  // TODO(dharcourt): Make the test utilities support 'error'.
+  // run.test('Errors results are spelled out', '1 / 0 = [[error]]');
+  // run.test('Addition treats errors as zero',
+  //          '1 / 0 = [error] + [0 + [0]] 123 = [123]');
+  // run.test('Subtraction treats errors as zero',
+  //          '1 / 0 = [error] - [0 - [0]] 123 = [-123]');
+  // run.test('Multiplication treats errors as zero',
+  //          '1 / 0 = [error] * [0 * [0]] 123 = [0]');
+  // run.test('Division treats errors as zero',
+  //          '1 / 0 = [error] / [0 / [0]] 123 = [0]');
+  // run.test('Equals treats errors as zero',
+  //         '1 / 0 = [error] = [0]');
+
+  // ---------------------------------------------------------------------------
+  // Test fixes for <http://crbug.com/156453>:
+
+  // run.test('Common operations are reversible',
+  //          '1 / 3 * 3 = [[1]]');
+
+  // run.test('Large numbers are displayed as exponentials',
+  //          '12345678 * 10 = [[1.23456e8]]');
+  // run.test('Small numbers are displayed as exponentials',
+  //          '0.0000001 / 10 = [[1e-8]]');
+
+  // ---------------------------------------------------------------------------
+  // Other tests.
+  // TODO(dharcourt): Organize and beef up these tests.
+  // TODO(dharcourt): Test {nega,posi}tive {under,over}flows.
 
   run.test("Initialization", function(model) {
     run.verify(null, model.accumulator, 'Accumulator');