feat: add ReturnType parser

factory/parser.ts

@@ -61,6 +61,7 @@ import { SatisfiesNodeParser } from "../src/NodeParser/SatisfiesNodeParser.js";
 import { PromiseNodeParser } from "../src/NodeParser/PromiseNodeParser.js";
 import { SpreadElementNodeParser } from "../src/NodeParser/SpreadElementNodeParser.js";
 import { IdentifierNodeParser } from "../src/NodeParser/IdentifierNodeParser.js";
+import { ReturnTypeNodeParser } from "../src/NodeParser/ReturnTypeNodeParser.js";
 
 export type ParserAugmentor = (parser: MutableParser) => void;
 
@@ -130,6 +131,7 @@ export function createParser(program: ts.Program, config: CompletedConfig, augme
         .addNodeParser(new ParenthesizedNodeParser(chainNodeParser))
 
         .addNodeParser(new PromiseNodeParser(typeChecker, chainNodeParser))
+        .addNodeParser(new ReturnTypeNodeParser(chainNodeParser, typeChecker))
         .addNodeParser(new TypeReferenceNodeParser(typeChecker, chainNodeParser))
         .addNodeParser(new ExpressionWithTypeArgumentsNodeParser(typeChecker, chainNodeParser))
         .addNodeParser(new IndexedAccessTypeNodeParser(typeChecker, chainNodeParser))

src/NodeParser/ReturnTypeNodeParser.ts

@@ -0,0 +1,116 @@
+import ts from "typescript";
+import type { Context, NodeParser } from "../NodeParser.js";
+import type { SubNodeParser } from "../SubNodeParser.js";
+import type { BaseType } from "../Type/BaseType.js";
+import { UnknownNodeError } from "../Error/Errors.js";
+
+export class ReturnTypeNodeParser implements SubNodeParser {
+    constructor(
+        private readonly childNodeParser: NodeParser,
+        private readonly checker: ts.TypeChecker,
+    ) {}
+
+    supportsNode(node: ts.Node): boolean {
+        if (!ts.isTypeReferenceNode(node)) {
+            return false;
+        }
+
+        const typeName = ts.isIdentifier(node.typeName) ? node.typeName.text : node.typeName.getText();
+        return typeName === "ReturnType" && node.typeArguments?.length === 1;
+    }
+
+    createType(node: ts.TypeReferenceNode, context: Context): BaseType {
+        if (!node.typeArguments || node.typeArguments.length !== 1) {
+            throw new UnknownNodeError(node);
+        }
+
+        const typeArg = node.typeArguments[0];
+
+        // Handle different types of type arguments
+        if (ts.isTypeQueryNode(typeArg)) {
+            // Case: ReturnType<typeof functionName>
+            // Get the symbol for the identifier
+            const symbol = this.checker.getSymbolAtLocation(typeArg.exprName);
+            if (!symbol) {
+                throw new UnknownNodeError(node);
+            }
+
+            // Get the declarations of the symbol
+            const declarations = symbol.getDeclarations() || [];
+
+            // Try multiple methods to extract return type
+            for (const decl of declarations) {
+                let returnTypeNode: ts.TypeNode | undefined;
+
+                // If declaration is a function/method with explicit return type
+                if (
+                    (ts.isFunctionDeclaration(decl) ||
+                        ts.isMethodDeclaration(decl) ||
+                        ts.isArrowFunction(decl) ||
+                        ts.isFunctionExpression(decl)) &&
+                    decl.type
+                ) {
+                    returnTypeNode = decl.type;
+                }
+                // If declaration is a variable with function type annotation
+                else if (ts.isVariableDeclaration(decl) && decl.type && ts.isFunctionTypeNode(decl.type)) {
+                    returnTypeNode = decl.type.type;
+                }
+
+                // If we found a return type node, process it
+                if (returnTypeNode) {
+                    const baseType = this.childNodeParser.createType(returnTypeNode, context);
+                    return baseType;
+                }
+            }
+
+            // Fallback to type checking method
+            const type = this.checker.getTypeOfSymbolAtLocation(symbol, typeArg);
+            const result = extractReturnTypeFromSignatures(type, this.checker, this.childNodeParser, context);
+            if (result) {
+                return result;
+            }
+        } else {
+            // Case: ReturnType<SomeType["methodName"]> or other complex types
+            // Get the type directly from TypeScript's type system
+            const argType = this.checker.getTypeAtLocation(typeArg);
+
+            // If it's a function type, get its return type
+            const result = extractReturnTypeFromSignatures(argType, this.checker, this.childNodeParser, context);
+            if (result) {
+                return result;
+            }
+
+            // Final fallback: try to get type directly
+            const type = this.checker.getTypeAtLocation(typeArg);
+            const typeNode = this.checker.typeToTypeNode(type, undefined, ts.NodeBuilderFlags.NoTruncation);
+
+            if (typeNode) {
+                return this.childNodeParser.createType(typeNode, context);
+            }
+        }
+
+        throw new UnknownNodeError(node);
+    }
+}
+
+/**
+ * Helper function to extract return type from call signatures
+ */
+function extractReturnTypeFromSignatures(
+    type: ts.Type,
+    checker: ts.TypeChecker,
+    childNodeParser: NodeParser,
+    context: Context,
+): BaseType | null {
+    const signatures = type.getCallSignatures();
+    if (signatures.length > 0) {
+        const returnType = signatures[0].getReturnType();
+        const returnTypeNode = checker.typeToTypeNode(returnType, undefined, ts.NodeBuilderFlags.NoTruncation);
+
+        if (returnTypeNode) {
+            return childNodeParser.createType(returnTypeNode, context);
+        }
+    }
+    return null;
+}

test/valid-data-type.test.ts

@@ -156,4 +156,9 @@ describe("valid-data-type", () => {
         "export-star-prune-unreachable",
         assertValidSchema("export-star-prune-unreachable", "*", undefined, { mainTsOnly: true }),
     );
+    it("type-return-type", assertValidSchema("type-return-type", "Greeting"));
+    it("type-return-type-complex", assertValidSchema("type-return-type-complex", "TestAppState"));
+    it("type-return-type-implicit", assertValidSchema("type-return-type-implicit", "ImplicitReturnType"));
+    it("type-return-type-function-parser", assertValidSchema("type-return-type-function", "FunctionReturnTypes"));
+    it("type-return-type-method", assertValidSchema("type-return-type-method", "MethodReturnTypes"));
 });

test/valid-data/type-return-type-complex/main.ts

@@ -0,0 +1,15 @@
+// Simulated Redux Toolkit scenario
+export interface TestState {
+    counter: number;
+    name: string;
+}
+
+export function createTestStore() {
+    return {
+        getState: () => ({ counter: 0, name: "test" }) as TestState,
+        dispatch: (action: any) => {},
+    };
+}
+
+export type TestAppStore = ReturnType<typeof createTestStore>;
+export type TestAppState = ReturnType<TestAppStore["getState"]>;

test/valid-data/type-return-type-complex/schema.json

@@ -0,0 +1,25 @@
+{
+  "$ref": "#/definitions/TestAppState",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "TestAppState": {
+      "$ref": "#/definitions/TestState"
+    },
+    "TestState": {
+      "additionalProperties": false,
+      "properties": {
+        "counter": {
+          "type": "number"
+        },
+        "name": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "counter",
+        "name"
+      ],
+      "type": "object"
+    }
+  }
+}

test/valid-data/type-return-type-function/main.ts

@@ -0,0 +1,44 @@
+// Test cases to demonstrate ReturnType parsing with various function types
+
+// Implicit return type
+export function implicitReturn() {
+    return { message: "Hello", count: 42 };
+}
+
+// Arrow function with implicit return
+export const arrowImplicitReturn = () => ({
+    nested: {
+        value: "test",
+        count: 123,
+    },
+});
+
+// Function expression with implicit return
+export const functionExprImplicitReturn = function () {
+    return {
+        dynamic: true,
+        payload: { id: 456, name: "example" },
+    };
+};
+
+// Complex nested return type with explicit annotation
+export function complexNestedReturn(): {
+    meta: {
+        version: number;
+        type: string;
+    };
+    data: string[];
+} {
+    return {
+        meta: { version: 1, type: "test" },
+        data: ["item1", "item2"],
+    };
+}
+
+// Combined type that tests all function return types
+export type FunctionReturnTypes = {
+    implicit: ReturnType<typeof implicitReturn>;
+    arrow: ReturnType<typeof arrowImplicitReturn>;
+    functionExpr: ReturnType<typeof functionExprImplicitReturn>;
+    complex: ReturnType<typeof complexNestedReturn>;
+};

test/valid-data/type-return-type-function/schema.json

@@ -0,0 +1,120 @@
+{
+  "$ref": "#/definitions/FunctionReturnTypes",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "FunctionReturnTypes": {
+      "additionalProperties": false,
+      "properties": {
+        "arrow": {
+          "additionalProperties": false,
+          "properties": {
+            "nested": {
+              "additionalProperties": false,
+              "properties": {
+                "count": {
+                  "type": "number"
+                },
+                "value": {
+                  "type": "string"
+                }
+              },
+              "required": [
+                "value",
+                "count"
+              ],
+              "type": "object"
+            }
+          },
+          "required": [
+            "nested"
+          ],
+          "type": "object"
+        },
+        "complex": {
+          "additionalProperties": false,
+          "properties": {
+            "data": {
+              "items": {
+                "type": "string"
+              },
+              "type": "array"
+            },
+            "meta": {
+              "additionalProperties": false,
+              "properties": {
+                "type": {
+                  "type": "string"
+                },
+                "version": {
+                  "type": "number"
+                }
+              },
+              "required": [
+                "version",
+                "type"
+              ],
+              "type": "object"
+            }
+          },
+          "required": [
+            "meta",
+            "data"
+          ],
+          "type": "object"
+        },
+        "functionExpr": {
+          "additionalProperties": false,
+          "properties": {
+            "dynamic": {
+              "type": "boolean"
+            },
+            "payload": {
+              "additionalProperties": false,
+              "properties": {
+                "id": {
+                  "type": "number"
+                },
+                "name": {
+                  "type": "string"
+                }
+              },
+              "required": [
+                "id",
+                "name"
+              ],
+              "type": "object"
+            }
+          },
+          "required": [
+            "dynamic",
+            "payload"
+          ],
+          "type": "object"
+        },
+        "implicit": {
+          "additionalProperties": false,
+          "properties": {
+            "count": {
+              "type": "number"
+            },
+            "message": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "message",
+            "count"
+          ],
+          "type": "object"
+        }
+      },
+      "required": [
+        "implicit",
+        "arrow",
+        "functionExpr",
+        "complex"
+      ],
+      "type": "object"
+    }
+  }
+}

test/valid-data/type-return-type-implicit/main.ts

@@ -0,0 +1,5 @@
+export function implicitReturn() {
+    return { message: "Hello", count: 42 };
+}
+
+export type ImplicitReturnType = ReturnType<typeof implicitReturn>;

test/valid-data/type-return-type-implicit/schema.json

@@ -0,0 +1,23 @@
+{
+  "$ref": "#/definitions/ImplicitReturnType",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "ImplicitReturnType": {
+      "additionalProperties": false,
+      "properties": {
+        "count": {
+          "type": "number"
+        },
+        "message": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "message",
+        "count"
+      ],
+      "type": "object"
+    }
+  }
+}
+