Testing best practices

Testing best practices

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Checking the size of a D3 Selection

The "length" of a D3 Selection is always 1, regardless of how many elements are in it:

d3.select().length; // 1, not 0

The correct way to check the size of the Selection is to assert that its size() is equal to a particular value:

assert.strictEquals(selection.size(), expectedSize, message);