Testing best practices

Testing best practices

Add more best practices here!

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);

Suggestions:

These are just suggestions of best practices, slowly move them upwards as people agree. In add proposer & agreers to each to have a sense of what is okay

• Top level describes should act as category delimiters and should not have beforeEach(). That is because sometime we want to add a new, totally unrelated test to some category (say Plots.Line) and the beforeEach() does not make sense. Top Level means the title of the file (so for example "Plots" and "RectanglePlot" will be top level) (@acioara)