Cyclomatic Complexity

Don’t write unnecessary tests anymore. Use a simple, scientific approach.

Transcript

1. foolab.ca | @foolabca
   Cyclomatic Complexity
   Bulgaria PHP, Sofia - October 8, 2016
   

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2. Execution Paths
   public function getShipping()
   {
   if ($this->subtotal >= 40) {
   return 0;
   }
   return $this->standardShipping;
   }
   2
   

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3. Execution Paths
   public function getShipping()
   {
   if ($this->subtotal >= 40) {
   return 0;
   }
   return $this->standardShipping;
   }
   3
   Path 1
   Path 2
   

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4. Decision Branches
   4
   start
   product loop
   free shipping?
   end
   

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5. Decision Branches
   5
   start
   product loop
   free shipping?
   end
   

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6. Cyclomatic complexity =
   edges − nodes +

   2 * connected components
   

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7. Decision Branches
   7
   start
   product loop
   free shipping?
   end
   ◦ Edges
   ◦ Nodes
   ◦ Connected components.
   

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8. Decision Branches
   8
   start
   product loop
   free shipping?
   end
   ◦ Edges
   ◦ Nodes
   ◦ Connected components.
   

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9. Decision Branches
   9
   start
   product loop
   free shipping?
   end
   ◦ Edges
   ◦ Nodes
   ◦ Connected components.
   

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10. Cyclomatic complexity =
    9 − 8 + 2 * 1 =
    3
    

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11. Zero Times
    foreach ($products as $product) {
    $total = $product->price * $product->quantity;
    }
    $tax = $total * ...
    11
    

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12. Multiple Times
    $total = 0;
    foreach ($products as $product) {
    $total = $product->price * $product->quantity;
    }
    $tax = $total * ...
    12
    

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13. Multiple Times
    $total = 0;
    foreach ($products as $product) {
    $total += $product->price * $product->quantity;
    }
    $tax = $total * ...
    13
    

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14. @afilina afilina.com
    

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