Make the object printing depth configurable (#2121)

Respect Node.js' `util.inspect.defaultOptions.depth` setting when printing objects.

docs/06-configuration.md

@@ -110,3 +110,21 @@ export default ({projectDir}) => {
 ```
 
 Note that the final configuration must not be a promise.
+
+## Object printing depth
+
+By default, AVA prints nested objects to a depth of `3`. However, when debugging tests with deeply nested objects, it can be useful to print with more detail. This can be done by setting [`util.inspect.defaultOptions.depth`](https://nodejs.org/api/util.html#util_util_inspect_defaultoptions) to the desired depth, before the test is executed:
+
+```js
+import util from 'util';
+
+import test from 'ava';
+
+util.inspect.defaultOptions.depth = 5;  // Increase AVA's printing depth
+
+test('My test', t => {
+	t.deepEqual(someDeeplyNestedObject, theExpectedValue);
+});
+```
+
+AVA has a minimum depth of `3`.

lib/concordance-options.js

@@ -1,4 +1,5 @@
 'use strict';
+const util = require('util');
 const ansiStyles = require('ansi-styles');
 const stripAnsi = require('strip-ansi');
 const cloneDeepWith = require('lodash.clonedeepwith');
@@ -124,6 +125,15 @@ const plainTheme = cloneDeepWith(colorTheme, value => {
 });
 
 const theme = chalk.enabled ? colorTheme : plainTheme;
-exports.default = {maxDepth: 3, plugins, theme};
+
+exports.default = {
+	// Use Node's object inspection depth, clamped to a minimum of 3
+	get maxDepth() {
+		return Math.max(3, util.inspect.defaultOptions.depth);
+	},
+	plugins,
+	theme
+};
+
 exports.diff = {maxDepth: 1, plugins, theme};
 exports.snapshotManager = {plugins, theme: plainTheme};