Legacy codesmalltalk

Legacy Code
Quit Complaining, Start Fixing

Saturday, February 15, 14

What Is Legacy Code?


34. }
35.
36. } else if (!data.getIsOffshore()) { // local
37.
38. cash = data.getCashBalance();
39.
40. investment = data.getInvestmentBalance();
41.


42. }
43.

44. if (<hidden>.getmCurrentExchangeRate().getRate().compareTo(newBigDecimal("0.0000")) == 1) {
45. // convert to current rate
46. cash = cash.divide(<hidden>.getmCurrentExchangeRate().getRate(),BigDecimal.ROUND_UP);
47. investment =investment.divide(<hidden>.getmCurrentExchangeRate().getRate(),
BigDecimal.ROUND_UP);
48. }
49.
50. // investment slice
51. item = new PieChartItem();
52. item.mLabel = res.getString(R.string.pcs_investment);
53. item.mSliceValue = investment;
54. item.mValue = investment.floatValue();
55. item.mColor = res.getColor(R.color.pcs_teal);
56. slices.add(item);
57.
58. // cash slice
59. item = new PieChartItem();
60. item.mLabel = res.getString(R.string.pcs_cash);
61. item.mSliceValue = cash;
62. item.mValue = cash.floatValue();
63. item.mColor = res.getColor(R.color.pcs_biscuit);
64. slices.add(item);
65.
66. mPieChartList.add(slices);
67. }
68.
69. }
70.


Code where the tests are an impediment,
not a benefit


Steps
Vent
But get it out of your system
Get it in a Harness
Verify the code around your new code
Add your Code


Seams
A place where you can change existing
behavior without editing code
Objects, Linker, Preprocessor
Enabling Point


var ParseRecurrenceDate = function (recurrencedata) {
var StartTime = DTSTART.exec(recurrencedata)[1];
var EndTime = DTEND.exec(recurrencedata)[1];
if (StartTime.indexOf("T") > 0) {
...
}
var EndDate = RRULE.exec(recurrencedata)[1];
EndDate = new Date(parseInt(EndDate.substr(0, 4), 10),
parseInt(EndDate.substr(4, 2), 10) - 1, parseInt(EndDate.substr(6, 2
10));


(will-mount [_]

        (let [{:keys [id-key filter tag-fn]} opts
              kill-chan (om/get-state owner :kill-chan)
              tx-chan (om/get-shared owner :tx-chan)
              txs (chan)]
          (assert (not (nil? tx-chan))
            "om-sync requires shared :tx-chan pub channel with :txs topic")
          (async/sub tx-chan :txs txs)
          (om/set-state! owner :txs txs)
          (go (loop []
                (let [dpath (om/path coll)
                      [{:keys [path new-value new-state] :as tx-data} _] (<! txs)
                      ppath (popn (- (count path) (inc (count dpath))) path)]
                  (when (and (subpath? dpath path)
                             (or (nil? filter) (filter tx-data)))
                    (let [tag (if-not (nil? tag-fn)


e void paintBackgroundDisabledAndWindowMaximized(Graphics2D g) {
    roundRect = decodeRoundRect1();
    g.setPaint(decodeGradient1(roundRect));
    g.fill(roundRect);
    g.fill(roundRect);
    rect = decodeRect1();
    g.setPaint(color4);
    g.fill(rect);
    g.setPaint(color5);
    g.fill(rect);


Adapt Parameter
Create New Interface That you can fake
Wrap Hard to instantiate class
Move to interfaces that communicate
responsibilities not implementation - to
avoid over-mocking


e void paintBackgroundDisabledAndWindowMaximized(GraphicsAdapter g) {
    g.fill(roundRect);
    g.fill(roundRect);
    g.setPaint(color4);
    g.fill(rect);
    g.setPaint(color5);
    g.fill(rect);


public class StubGraphicsAdapter implements GraphicsAdapter {

public void setPaint(java.awt.Color color) {
}
...
}

public class JavaAwtGraphicsAdapter implements GraphicsAdapter {
private Graphics2D g;
public JavaAwtGraphicsAdapter(Graphics2D g) {
this.g = g;
}
public void setPaint(java.awt.Color color) {
this.g.setPaint(color);
}


UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Signup Unsuccessful"
message:reason
delegate:NULL
cancelButtonTitle:@"OK"
otherButtonTitles:NULL];


Extract and Override
Identify the call you want to extract
Create a new method on the current class
Override in test


UIAlertView *alert =[[[[self class] alertViewClass] alloc] initWithTitle:@"Signup
message:reason
delegate:NULL
cancelButtonTitle:@"OK"
otherButtonTitles:NULL];


+(Class) alertViewClass
{
return [UIAlertView class];
}

// In test file
@interface LoginViewControllerWithTestAlert : LoginViewController
@end

@implementation LoginViewControllerWithTestAlert

+(Class) alertViewClass
{
return [TestAlert class];
}

@end


Static Setter
Allow Subclassing a Singleton
Add a Static Setter
Add a Clear or Reset to avoid Test
Pollution


void MessageRouter::route(Message *message) {
Dispatcher *dispatcher =
ExternalRouter::instance()->getDispatcher();
if (dispatcher != NULL)
dispatcher->sendMessage(message;
}


class ExternalRouter
{
private:
static ExternalRouter *_instance;

ExternalRouter();
public:
static ExternalRouter *instance();
}

ExternalRouter *ExternalRouter::_instance = 0;

ExternalRouter *ExternalRouter::instance()
{
if (_instance == 0) {
_instance = new ExternalRouter();
}
return _instance;
}


class ExternalRouter
{
private:
static ExternalRouter *_instance;
protected:
ExternalRouter();
public:
static ExternalRouter *instance();
static void setTestingInstance(ExternalRouter *newInstance);
}

void ExternalRouter::setTestingInstance(ExternalRouter *newInstance)
{
delete _instance;
_instance = newInstance;
}

class TestingExternalRouter : public ExternalRouter
{
public:
virtual void Dispatcher *getDispatcher() const {
return new FakeDispatcher();
}
}


Higher Level Tests

Characterization Tests
In case of emergency break glass.


Resources
Working Effectively With Legacy Code
- Michael Feathers
http://www.reddit.com/r/badcode
@paytonrules (that’s me)
Bullets suck


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