fix(seed): stop go-sdk idempotency-headers fixture from overwriting its nested config

packages/seed/src/__test__/validateFixtureOutputFolders.test.ts

@@ -0,0 +1,43 @@
+import { FernSeedConfig } from "../config/index.js";
+import { validateFixtureOutputFolders } from "../validateFixtureOutputFolders.js";
+
+function workspaceConfig(
+    fixtures: Record<string, FernSeedConfig.FixtureConfigurations[]>
+): FernSeedConfig.SeedWorkspaceConfiguration {
+    return { fixtures } as FernSeedConfig.SeedWorkspaceConfiguration;
+}
+
+describe("validateFixtureOutputFolders", () => {
+    it("allows a single configuration writing to the fixture root", () => {
+        const errors = validateFixtureOutputFolders({
+            workspaceName: "go-sdk",
+            workspaceConfig: workspaceConfig({ streaming: [{ outputFolder: "." }] })
+        });
+        expect(errors).toEqual([]);
+    });
+
+    it("allows multiple configurations in distinct output folders", () => {
+        const errors = validateFixtureOutputFolders({
+            workspaceName: "go-sdk",
+            workspaceConfig: workspaceConfig({
+                "idempotency-headers": [
+                    { outputFolder: "no-custom-config" },
+                    { outputFolder: "auto-generate-idempotency-key" }
+                ]
+            })
+        });
+        expect(errors).toEqual([]);
+    });
+
+    it("rejects a configuration writing to the fixture root alongside a nested configuration", () => {
+        const errors = validateFixtureOutputFolders({
+            workspaceName: "go-sdk",
+            workspaceConfig: workspaceConfig({
+                "idempotency-headers": [{ outputFolder: "." }, { outputFolder: "auto-generate-idempotency-key" }]
+            })
+        });
+        expect(errors).toHaveLength(1);
+        expect(errors[0]).toContain('fixture "idempotency-headers"');
+        expect(errors[0]).toContain('"auto-generate-idempotency-key"');
+    });
+});

packages/seed/src/loadGeneratorWorkspaces.ts

@@ -5,6 +5,7 @@ import { access, readdir, readFile } from "fs/promises";
 import yaml from "js-yaml";
 
 import { FernSeedConfig } from "./config/index.js";
+import { validateFixtureOutputFolders } from "./validateFixtureOutputFolders.js";
 
 export interface GeneratorWorkspace {
     workspaceName: string;
@@ -59,6 +60,10 @@ export async function loadGeneratorWorkspaces(): Promise<GeneratorWorkspace[]> {
             CONSOLE_LOGGER.warn(`Skipping ${workspace}: disabled in ${SEED_CONFIG_FILENAME}`);
             continue;
         }
+        const errors = validateFixtureOutputFolders({ workspaceName: workspace, workspaceConfig });
+        if (errors.length > 0) {
+            throw new Error(`Invalid ${SEED_CONFIG_FILENAME}:\n${errors.join("\n")}`);
+        }
         workspaces.push({
             absolutePathToWorkspace,
             workspaceConfig,

packages/seed/src/validateFixtureOutputFolders.ts

@@ -0,0 +1,29 @@
+import { FernSeedConfig } from "./config/index.js";
+
+/**
+ * Generation wipes a fixture's output folder before writing files, so a configuration
+ * that writes to the fixture root ("." ) destroys the output of any sibling configuration
+ * nested underneath it.
+ */
+export function validateFixtureOutputFolders({
+    workspaceName,
+    workspaceConfig
+}: {
+    workspaceName: string;
+    workspaceConfig: FernSeedConfig.SeedWorkspaceConfiguration;
+}): string[] {
+    const errors: string[] = [];
+    for (const [fixture, configurations] of Object.entries(workspaceConfig.fixtures ?? {})) {
+        const outputFolders = configurations.map((configuration) => configuration.outputFolder);
+        if (outputFolders.length > 1 && outputFolders.includes(".")) {
+            errors.push(
+                `${workspaceName}: fixture "${fixture}" has an outputFolder of "." alongside ${outputFolders
+                    .filter((outputFolder) => outputFolder !== ".")
+                    .map((outputFolder) => `"${outputFolder}"`)
+                    .join(", ")}. ` +
+                    `Give every configuration its own output folder so they do not overwrite each other.`
+            );
+        }
+    }
+    return errors;
+}

seed/go-sdk/seed.yml

@@ -268,7 +268,7 @@ fixtures:
     - outputFolder: no-custom-config
       customConfig: null
   idempotency-headers:
-    - outputFolder: .
+    - outputFolder: no-custom-config
       outputVersion: 0.0.1
       customConfig:
         packageName: fern