From b752aabc47c0f2551377a56ed815e96e3ae3a2c1 Mon Sep 17 00:00:00 2001
From: Daniel Chambers <daniel@hasura.io>
Date: Wed, 10 Apr 2024 23:48:40 +1000
Subject: [PATCH] Fixed functions that are imported then re-exported causing a
 crash (#28)

---
 CHANGELOG.md                                  |  1 +
 ndc-lambda-sdk/src/inference.ts               |  6 +-
 .../functions-import-then-export.ts           |  8 +++
 .../re-exported-functions.test.ts             | 63 ++++++++++++++++++-
 4 files changed, 76 insertions(+), 2 deletions(-)
 create mode 100644 ndc-lambda-sdk/test/inference/re-exported-functions/functions-import-then-export.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 044ade2..25a987d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ This changelog documents the changes between release versions.
 Changes to be included in the next upcoming release
 
 - Fixed watch mode not reloading after files with compiler errors are changed [#27](https://github.com/hasura/ndc-nodejs-lambda/pull/27)
+- Fixed functions that are imported then re-exported causing a crash [#28](https://github.com/hasura/ndc-nodejs-lambda/pull/28)
 
 ## [1.2.0] - 2024-03-18
 - Improved error messages when unsupported enum types or unions of literal types are found, and allow these types to be used in relaxed types mode ([#17](https://github.com/hasura/ndc-nodejs-lambda/pull/17))
diff --git a/ndc-lambda-sdk/src/inference.ts b/ndc-lambda-sdk/src/inference.ts
index 1887a46..d032d48 100644
--- a/ndc-lambda-sdk/src/inference.ts
+++ b/ndc-lambda-sdk/src/inference.ts
@@ -171,10 +171,14 @@ function deriveSchemaFromFunctions(sourceFile: ts.SourceFile, projectRootDir: st
     const declaration = exportedSymbol.getDeclarations()?.[0] ?? throwError("exported symbol does not have a declaration");
 
     // If exported via 'export { name } from "./imported"'
+    // or 'import { name } from "./imported"; export { name }'
     if (ts.isExportSpecifier(declaration)) {
       const identifier = declaration.name ?? throwError("export declaration didn't have an identifier");
       const exportTarget = typeChecker.getExportSpecifierLocalTargetSymbol(declaration) ?? throwError("export specifier does not have a local target symbol");
-      const exportTargetDeclaration = exportTarget.valueDeclaration ?? throwError("export target symbol does not have a value declaration");
+      const exportTargetDeclaration =
+        exportTarget.valueDeclaration // 'export { name } from "./imported"'
+        ?? typeChecker.getAliasedSymbol(exportTarget).valueDeclaration // 'import { name } from "./imported"; export { name }'
+        ?? throwError("export target symbol does not have a value declaration");
       if (ts.isFunctionDeclaration(exportTargetDeclaration)) {
         return [[identifier.text, exportTargetDeclaration]];
       }
diff --git a/ndc-lambda-sdk/test/inference/re-exported-functions/functions-import-then-export.ts b/ndc-lambda-sdk/test/inference/re-exported-functions/functions-import-then-export.ts
new file mode 100644
index 0000000..3d46037
--- /dev/null
+++ b/ndc-lambda-sdk/test/inference/re-exported-functions/functions-import-then-export.ts
@@ -0,0 +1,8 @@
+import { fileAChildFunction as renamedFileAChildFunction } from "./file-a"
+import { fileBChildFunction1, fileBChildFunction2 } from "./file-b"
+
+export {
+  renamedFileAChildFunction,
+  fileBChildFunction1,
+  fileBChildFunction2 as renamedFileBChildFunction2
+};
diff --git a/ndc-lambda-sdk/test/inference/re-exported-functions/re-exported-functions.test.ts b/ndc-lambda-sdk/test/inference/re-exported-functions/re-exported-functions.test.ts
index 0d1246a..da17537 100644
--- a/ndc-lambda-sdk/test/inference/re-exported-functions/re-exported-functions.test.ts
+++ b/ndc-lambda-sdk/test/inference/re-exported-functions/re-exported-functions.test.ts
@@ -1,7 +1,7 @@
 import { describe, it } from "mocha";
 import { assert } from "chai";
 import { deriveSchema } from "../../../src/inference";
-import { BuiltInScalarTypeName, FunctionNdcKind, NullOrUndefinability } from "../../../src/schema";
+import { FunctionNdcKind } from "../../../src/schema";
 
 describe("re-exported functions", function() {
   it("supports functions re-exported from other files", function() {
@@ -206,4 +206,65 @@ describe("re-exported functions", function() {
       }
     })
   });
+
+  it("supports re-exports of functions from other files that are first imported then exported", function() {
+    const schema = deriveSchema(require.resolve("./functions-import-then-export.ts"));
+
+    assert.deepStrictEqual(schema, {
+      compilerDiagnostics: [],
+      functionIssues: {},
+      functionsSchema: {
+        functions: {
+          "renamedFileAChildFunction": {
+            ndcKind: FunctionNdcKind.Procedure,
+            description: null,
+            parallelDegree: null,
+            arguments: [],
+            resultType: {
+              name: "String",
+              kind: "scalar",
+              type: "named",
+            }
+          },
+          "fileBChildFunction1": {
+            ndcKind: FunctionNdcKind.Procedure,
+            description: null,
+            parallelDegree: null,
+            arguments: [],
+            resultType: {
+              name: "Boolean",
+              kind: "scalar",
+              type: "named",
+            }
+          },
+          "renamedFileBChildFunction2": {
+            ndcKind: FunctionNdcKind.Function,
+            description: null,
+            parallelDegree: null,
+            arguments: [
+              {
+                argumentName: "input",
+                description: null,
+                type: {
+                  name: "String",
+                  kind: "scalar",
+                  type: "named",
+                }
+              }
+            ],
+            resultType: {
+              name: "String",
+              kind: "scalar",
+              type: "named",
+            }
+          },
+        },
+        scalarTypes: {
+          Boolean: { type: "built-in" },
+          String: { type: "built-in" },
+        },
+        objectTypes: {},
+      }
+    })
+  });
 });