References tests: Add custom diff printer

This is an ugly workaroud for jestjs/jest#10276.

src/utils/if-curtailed.ts

@@ -0,0 +1,18 @@
+/**
+ * Invoke @param fn and return the result. If the function is curtailed, invoke @param handler before letting things happen.
+ *
+ * Adoption of Smalltalk's `BlockClosure >> #ifCurtailed:`.
+*/
+export default function ifCurtailed<T>(fn: () => T, handler: () => void): T {
+    let complete = false
+    let result: T
+    try {
+        result = fn()
+        complete = true
+    } finally {
+        if (complete != true) {
+            handler()
+        }
+    }
+    return result
+}

test/_utils/printDiff.ts

@@ -0,0 +1,36 @@
+/** @XXX Cheap and very imprecise workaround for https://github.com/facebook/jest/issues/10276 */
+export function printDiff(actual: unknown, expected: unknown, ...context: unknown[]) {
+    console.log([...context, ...createDiff(actual, expected)].join("\n"))
+}
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+function* createDiff(actual: any, expected: any, level = 0): Generator<string> {
+    const indent = ' '.repeat(level)
+
+    if (!(expected.sample)) {
+        if (actual != expected) {
+            // Only show diffs
+            yield `${indent}${actual} != ${expected}`
+        }
+        return
+    }
+    if (Array.isArray(actual)) {
+        for (const expectedObject of expected.sample) {
+            yield `${indent}${expectedObject}:`
+            if (actual.includes(expectedObject)) {
+                continue
+            }
+            yield `${indent} MISSING: ${expectedObject}`
+        }
+        return
+    }
+
+    for (const [expectedKey, expectedObject] of Object.entries(expected.sample)) {
+        yield `${indent}${expectedKey}:`
+        if (expectedKey in actual) {
+            yield* createDiff(actual[expectedKey], expectedObject, level + 1)
+            continue
+        }
+        yield `${indent} MISSING: ${expectedKey}`
+    }
+}

test/references.test.ts

@@ -2,6 +2,8 @@ import asyncIteratorToArray from 'it-all'
 import _ from 'lodash'
 
 import { ReferenceSearcher } from '../src/references'
+import ifCurtailed from '../src/utils/if-curtailed'
+import { printDiff } from './_utils/printDiff'
 
 import expectedHeuristicReferences from './references.test/expectedReferences-heuristic.json'
 
@@ -42,13 +44,15 @@ describe('ReferenceSearcher', () => {
                 .value())
             .value()
 
-        expect(aggregatedReferences).toEqual(
-            expect.objectContaining(
-                _.mapValues(expectedReferences, dependentReferences => expect.objectContaining(
-                    _.mapValues(dependentReferences, memberReferences => expect.objectContaining(
-                        _.mapValues(memberReferences, lineNumbers => expect.arrayContaining(lineNumbers))
-                    ))
-                ))))
-        // TODO: Test false positive rate?
+        const aggregatedExpectedReferences = expect.objectContaining(
+            _.mapValues(expectedReferences, dependentReferences => expect.objectContaining(
+                _.mapValues(dependentReferences, memberReferences => expect.objectContaining(
+                    _.mapValues(memberReferences, lineNumbers => expect.arrayContaining(lineNumbers))
+                ))
+            )))
+        ifCurtailed(
+            () => expect(aggregatedReferences).toEqual(aggregatedExpectedReferences),
+            () => printDiff(aggregatedReferences, aggregatedExpectedReferences, packageReferenceSearcher, packageName))
+        // TODO: Test false positive rate
     })
 })