Replace Enzyme with React Testing Library

[becca-bailey]

In addition to some of the general issues with our tests being a little slow and out of date, we will need to replace Enzyme as our method of rendering components in tests if we want to upgrade to React 18+.

We should re-write our existing tests using Jest + React Testing Library.

Related issue: #2187

See also: https://dev.to/wojtekmaj/enzyme-is-dead-now-what-ekl

Completed packages

• victory
• victory-area
• victory-bar
• victory-box-plot
• victory-brush-container
• victory-candlestick
• victory-chart
• victory-core
• victory-errorbars
• victory-group
• victory-histogram
• victory-legend
• victory-line
• victory-pie
• victory-scatter
• victory-selection-container
• victory-shared-events (this might be going away soon, so it's a lower priority test suite to convert)
• victory-stack
• victory-tooltip
• victory-voronoi

General tips and pointers

• We can use querySelector in a test to test attributes on SVG elements.
• We can also use getByRole or getByTestId to isolate specific nodes. Add safe user props to all top-level components #2191 should allow us to add data-testid to our test components, but there may be some primitive components that need to be set up to work with these user-provided props.
• We can replace some of the test assertions with .toMatchInlineSnapshot, provided that the snapshot is focused (< 10 lines) and easy to read.
• If we want to test the data that is being passed to the SVG component, there are some workarounds we can use, such as giving our test component a property that outputs the rendered data as JSON. Here is an example:

it("renders data ordered by value of sortKey, if given", () => {
      const data = [{ t: 0 /*x: 10, y: 1*/ }, { t: 1 /*x:  9, y: 1*/ }];
      const { container } = render(
        <VictoryLine
          data={data}
          sortKey="t"
          x={({ t }) => 10 - t}
          y={() => 1}
          dataComponent={
            <Curve data-json={(props) => JSON.stringify(props.data)} />
          }
        />
      );

      const line = container.querySelector("path");
      const renderedData = JSON.parse(line.getAttribute("data-json")).map(
        ({ t }) => t
      );

      expect(renderedData).toEqual([0, 1]);
    });

Long-term, we might want to figure out how to test data transformations in a different place.

[heythisispaul]

@becca-bailey I can start work on victory-bar.

[heythisispaul]

#2216 for victory-bar tests should be good to go, I'm moving on to victory-box-plot.

[becca-bailey]

I'm going to start work on victory-core.

[becca-bailey]

I am working on victory-errorbar next.

[heythisispaul]

I'm picking up victory-histogram now

[heythisispaul]

#2255 is up for the histogram tests, moving on to victory-legend

[heythisispaul]

Moving on to victory-pie

[becca-bailey]

The modules that were excluded from this conversion are add-events and victory-shared-events, due to their heavy reliance on mocking and class inheritance. We are going to re-write those tests once we refactor Victory events and state management.