fix(core): stop heuristically merging distinct named top-level classes

packages/quicktype-core/src/rewrites/CombineClasses.ts

@@ -108,7 +108,15 @@ function tryAddToClique(
     c: ClassType,
     clique: Clique,
     onlyWithSameProperties: boolean,
+    topLevels: ReadonlySet<Type>,
 ): boolean {
+    if (
+        topLevels.has(c) &&
+        clique.members.some((member) => topLevels.has(member))
+    ) {
+        return false;
+    }
+
     for (const prototype of clique.prototypes) {
         if (prototype.structurallyCompatible(c)) {
             clique.members.push(c);
@@ -132,6 +140,10 @@ function findSimilarityCliques(
     onlyWithSameProperties: boolean,
     includeFixedClasses: boolean,
 ): ClassType[][] {
+    // Distinct named top-levels must not be heuristically combined.  Exactly
+    // identical top-levels can already have been deduplicated during inference.
+    // Top-levels can still combine with nested classes to preserve recursion.
+    const topLevels = new Set(graph.topLevels.values());
     const classCandidates = Array.from(
         graph.allNamedTypesSeparated().objects,
     ).filter(
@@ -142,7 +154,9 @@ function findSimilarityCliques(
     for (const c of classCandidates) {
         let cliqueIndex: number | undefined;
         for (let i = 0; i < cliques.length; i++) {
-            if (tryAddToClique(c, cliques[i], onlyWithSameProperties)) {
+            if (
+                tryAddToClique(c, cliques[i], onlyWithSameProperties, topLevels)
+            ) {
                 cliqueIndex = i;
                 break;
             }

test/fixtures.ts

@@ -351,6 +351,89 @@ abstract class LanguageFixture extends Fixture {
     }
 }
 
+class MultipleJSONTopLevelsFixture extends LanguageFixture {
+    readonly name = "csharp-multiple-json-top-levels";
+    private readonly fixtureDirectory = "test/inputs/json/priority/issue-1630";
+
+    constructor() {
+        super({
+            ...languages.CSharpLanguageSystemTextJson,
+            base: "test/fixtures/csharp-multiple-json-top-levels",
+        });
+    }
+
+    runForName(name: string): boolean {
+        return (
+            name === this.name ||
+            name === "csharp-SystemTextJson" ||
+            name === "json"
+        );
+    }
+
+    getSamples(sources: string[]): { priority: Sample[]; others: Sample[] } {
+        if (sources.length > 0) return { priority: [], others: [] };
+
+        return {
+            priority: [
+                {
+                    path: this.fixtureDirectory,
+                    additionalRendererOptions: {},
+                    saveOutput: true,
+                },
+            ],
+            others: [],
+        };
+    }
+
+    shouldSkipTest(_sample: Sample): boolean {
+        return false;
+    }
+
+    async runQuicktype(
+        directory: string,
+        additionalRendererOptions: RendererOptions,
+    ): Promise<void> {
+        await quicktype({
+            srcLang: "json",
+            lang: this.language.name,
+            src: [directory],
+            out: this.language.output,
+            alphabetizeProperties: true,
+            rendererOptions: _.merge(
+                {},
+                this.language.rendererOptions,
+                additionalRendererOptions,
+            ),
+            quiet: true,
+            telemetry: "disable",
+            debug: "provenance",
+        });
+    }
+
+    async test(
+        directory: string,
+        additionalRendererOptions: RendererOptions,
+        _additionalFiles: string[],
+    ): Promise<number> {
+        if (this.language.compileCommand) {
+            await execAsync(this.language.compileCommand);
+        }
+
+        const samples = testsInDir(directory, "json");
+        for (const sample of samples) {
+            compareJsonFileToJson(
+                comparisonArgs(
+                    this.language,
+                    sample,
+                    sample,
+                    additionalRendererOptions,
+                ),
+            );
+        }
+        return samples.length;
+    }
+}
+
 class JSONFixture extends LanguageFixture {
     constructor(
         language: languages.Language,
@@ -1742,6 +1825,7 @@ export const allFixtures: Fixture[] = [
         languages.CSharpLanguageSystemTextJson,
         "csharp-SystemTextJson",
     ),
+    new MultipleJSONTopLevelsFixture(),
     new JSONFixture(languages.JavaLanguage),
     new JSONFixture(
         languages.JavaLanguageWithLegacyDateTime,

test/fixtures/csharp-multiple-json-top-levels/.gitignore

@@ -0,0 +1,2 @@
+bin
+obj

test/fixtures/csharp-multiple-json-top-levels/Program.cs

@@ -0,0 +1,43 @@
+using System;
+using System.IO;
+
+namespace QuickType
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            var path = args[0];
+            var json = File.ReadAllText(path);
+            string output;
+
+            switch (Path.GetFileName(path))
+            {
+                case "AccountsGet.Request.json":
+                {
+                    AccountsGetRequest value = AccountsGetRequest.FromJson(json);
+                    output = value.ToJson();
+                    break;
+                }
+                case "AuthGet.Request.json":
+                {
+                    AuthGetRequest value = AuthGetRequest.FromJson(json);
+                    AuthGetRequestOptions options = value.Options;
+                    output = value.ToJson();
+                    break;
+                }
+                case "TransactionsGet.Request.json":
+                {
+                    TransactionsGetRequest value = TransactionsGetRequest.FromJson(json);
+                    TransactionsGetRequestOptions options = value.Options;
+                    output = value.ToJson();
+                    break;
+                }
+                default:
+                    throw new ArgumentException($"Unexpected fixture input: {path}");
+            }
+
+            Console.WriteLine(output);
+        }
+    }
+}

test/fixtures/csharp-multiple-json-top-levels/test.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="System.Text.Json" Version="8.0.5" />
+  </ItemGroup>
+</Project>

test/inputs/json/priority/issue-1630/AccountsGet.Request.json

@@ -0,0 +1,5 @@
+{
+    "client_id": "1234abcd5678efgh90ij",
+    "secret": "1234abcd5678efgh90ij",
+    "access_token": "1234abcd5678efgh90ij"
+}

test/inputs/json/priority/issue-1630/AuthGet.Request.json

@@ -0,0 +1,8 @@
+{
+    "client_id": "1234abcd5678efgh90ij",
+    "secret": "1234abcd5678efgh90ij",
+    "access_token": "1234abcd5678efgh90ij",
+    "options": {
+        "account_ids": ["abc", "def", "ghi"]
+    }
+}

test/inputs/json/priority/issue-1630/TransactionsGet.Request.json

@@ -0,0 +1,12 @@
+{
+    "client_id": "1234abcd5678efgh90ij",
+    "secret": "1234abcd5678efgh90ij",
+    "access_token": "1234abcd5678efgh90ij",
+    "start_date": "2020-01-01",
+    "end_date": "2020-01-31",
+    "options": {
+        "account_ids": ["abc", "def", "ghi"],
+        "count": 100,
+        "offset": 0
+    }
+}