test: cover config loader interpolation

tests/config/loader.test.js

@@ -0,0 +1,82 @@
+import fs from "fs";
+import os from "os";
+import path from "path";
+
+import { loadConfig } from "../../src/config/loader.js";
+
+describe("loadConfig", () => {
+  let originalCwd;
+  let tempDir;
+  let originalEnv;
+
+  beforeEach(() => {
+    originalCwd = process.cwd();
+    originalEnv = { ...process.env };
+    tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "apidrift-config-"));
+    process.chdir(tempDir);
+  });
+
+  afterEach(() => {
+    process.chdir(originalCwd);
+    process.env = originalEnv;
+    fs.rmSync(tempDir, { recursive: true, force: true });
+  });
+
+  test("returns the default config when apidrift.config.json is missing", () => {
+    expect(loadConfig()).toEqual({
+      environments: {},
+      endpoints: [],
+      discovery: "heuristic",
+    });
+  });
+
+  test("interpolates environment variables in config values", () => {
+    process.env.API_BASE_URL = "https://api.example.com";
+    process.env.AUTH_TOKEN = "secret-token";
+
+    fs.writeFileSync(
+      "apidrift.config.json",
+      JSON.stringify({
+        environments: {
+          production: {
+            baseUrl: "${API_BASE_URL}",
+            headers: {
+              Authorization: "Bearer ${AUTH_TOKEN}",
+            },
+          },
+        },
+        endpoints: ["/users"],
+        discovery: "openapi",
+      }),
+    );
+
+    expect(loadConfig()).toEqual({
+      environments: {
+        production: {
+          baseUrl: "https://api.example.com",
+          headers: {
+            Authorization: "Bearer secret-token",
+          },
+        },
+      },
+      endpoints: ["/users"],
+      discovery: "openapi",
+    });
+  });
+
+  test("replaces missing environment variables with empty strings", () => {
+    fs.writeFileSync(
+      "apidrift.config.json",
+      JSON.stringify({
+        environments: {
+          local: {
+            baseUrl: "${MISSING_API_URL}",
+          },
+        },
+        endpoints: [],
+      }),
+    );
+
+    expect(loadConfig().environments.local.baseUrl).toBe("");
+  });
+});