add error handling test

Author: kamiazya

src/components/__tests__/Digraph.spec.tsx

@@ -0,0 +1,16 @@
+import React from 'react';
+import { Digraph } from '../Digraph';
+import { DuplicatedRootClusterErrorMessage } from '../../utils/errors';
+import { renderExpectToThrow } from './utils/renderExpectToThrow';
+
+describe('Digraph', () => {
+  // eslint-disable-next-line jest/expect-expect
+  test('An error occurs when duplicate <Digraph />', () => {
+    renderExpectToThrow(
+      <Digraph>
+        <Digraph />
+      </Digraph>,
+      DuplicatedRootClusterErrorMessage,
+    );
+  });
+});

src/components/__tests__/Graph.spec.tsx

@@ -0,0 +1,16 @@
+import React from 'react';
+import { Graph } from '../Graph';
+import { DuplicatedRootClusterErrorMessage } from '../../utils/errors';
+import { renderExpectToThrow } from './utils/renderExpectToThrow';
+
+describe('Graph', () => {
+  // eslint-disable-next-line jest/expect-expect
+  test('An error occurs when duplicate <Graph />', () => {
+    renderExpectToThrow(
+      <Graph>
+        <Graph />
+      </Graph>,
+      DuplicatedRootClusterErrorMessage,
+    );
+  });
+});

src/components/__tests__/utils/renderExpectToThrow.tsx

@@ -0,0 +1,40 @@
+/* eslint-disable react/destructuring-assignment */
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
+import React, { Component, ReactElement } from 'react';
+import { Context } from 'ts-graphviz';
+import { render } from '../../../renderer/render';
+
+export function renderExpectToThrow(element: ReactElement, expectedError: string) {
+  const errors: Error[] = [];
+  class ErrorBoundary extends Component<{}, { hasError: boolean }> {
+    constructor(props: {}) {
+      super(props);
+      this.state = { hasError: false };
+    }
+
+    static getDerivedStateFromError() {
+      return { hasError: true };
+    }
+
+    componentDidCatch(error: Error) {
+      errors.push(error);
+    }
+
+    render() {
+      if (this.state.hasError) {
+        return <></>;
+      }
+      return this.props.children;
+    }
+  }
+
+  const context = new Context();
+  try {
+    render(<ErrorBoundary>{element}</ErrorBoundary>, context);
+  } catch (e) {
+    errors.push(e);
+  }
+
+  expect(errors.length).toBe(1);
+  expect(errors[0].message).toContain(expectedError);
+}

…sts__/__snapshots__/to-dot.spec.tsx.snap …_snapshots__/render-to-dot.spec.tsx.snapsrc/renderer/__tests__/__snapshots__/to-dot.spec.tsx.snap renamed to src/renderer/__tests__/__snapshots__/render-to-dot.spec.tsx.snap src/renderer/__tests__/__snapshots__/to-dot.spec.tsx.snap renamed to src/renderer/__tests__/__snapshots__/render-to-dot.spec.tsx.snap

@@ -1,14 +1,14 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`toDot render edge 1`] = `
+exports[`renderToDot render edge 1`] = `
 digraph {
   "a";
   "b";
   "a" -> "b";
 }
 `;
 
-exports[`toDot render subgraph 1`] = `
+exports[`renderToDot render subgraph 1`] = `
 digraph {
   subgraph {
     "a";
@@ -18,7 +18,7 @@ digraph {
 }
 `;
 
-exports[`toDot render works 1`] = `
+exports[`renderToDot render works 1`] = `
 digraph {
   "a";
   "b";

src/renderer/__tests__/to-dot.spec.tsx …enderer/__tests__/render-to-dot.spec.tsxsrc/renderer/__tests__/to-dot.spec.tsx renamed to src/renderer/__tests__/render-to-dot.spec.tsx src/renderer/__tests__/to-dot.spec.tsx renamed to src/renderer/__tests__/render-to-dot.spec.tsx

@@ -7,7 +7,7 @@ import { Digraph } from '../../components/Digraph';
 import { Node } from '../../components/Node';
 import { renderToDot } from '../render';
 
-describe('toDot', () => {
+describe('renderToDot', () => {
   it('render works', () => {
     const dot = renderToDot(
       <Digraph>
@@ -45,4 +45,9 @@ describe('toDot', () => {
     );
     expect(dot).toBeValidDotAndMatchSnapshot();
   });
+
+  it('render to be blank string', () => {
+    const dot = renderToDot(<></>);
+    expect(dot).toBe('');
+  });
 });