Add restriction for allowed separators in configuration object construction

Author: Eskibear

src/AzureAppConfiguration.ts

@@ -29,10 +29,10 @@ interface IConfigurationObject {
 export interface ConfigurationObjectConstructionOptions {
     /**
      * The separator to use when converting hierarchical keys to object properties.
+     * Supported values: '.', ',', ';', '-', '_', '__', '/', ':'.
      * If separator is undefined, '.' will be used by default.
-
      */
-    separator?: string;
+    separator?: "." | "," | ";" | "-" | "_" | "__" | "/" | ":";
 }
 
 interface IGettable {

src/AzureAppConfigurationImpl.ts

@@ -184,6 +184,10 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
      */
     constructConfigurationObject(options?: ConfigurationObjectConstructionOptions): Record<string, any> {
         const separator = options?.separator ?? ".";
+        const validSeparators = [".", ",", ";", "-", "_", "__", "/", ":"];
+        if (!validSeparators.includes(separator)) {
+            throw new Error(`Invalid separator '${separator}'. Supported values: ${validSeparators.map(s => `'${s}'`).join(", ")}.`);
+        }
 
         // construct hierarchical data object from map
         const data: Record<string, any> = {};

test/load.test.ts

@@ -14,6 +14,18 @@ const mockedKVs = [{
 }, {
     key: "app.settings.fontSize",
     value: "40",
+}, {
+    key: "app/settings/fontColor",
+    value: "red",
+}, {
+    key: "app/settings/fontSize",
+    value: "40",
+}, {
+    key: "app%settings%fontColor",
+    value: "red",
+}, {
+    key: "app%settings%fontSize",
+    value: "40",
 }, {
     key: "TestKey",
     label: "Test",
@@ -50,7 +62,7 @@ const mockedKVs = [{
 }, {
     key: "app5.settings",
     value: "placeholder"
-},
+}
 ].map(createMockedKeyValue);
 
 describe("load", function () {
@@ -287,4 +299,36 @@ describe("load", function () {
         expect(data.app4.excludedFolders[0]).eq("node_modules");
         expect(data.app4.excludedFolders[1]).eq("dist");
     });
+
+    it("should construct configuration object with customized separator", async () => {
+        const connectionString = createMockedConnectionString();
+        const settings = await load(connectionString, {
+            selectors: [{
+                keyFilter: "app/settings/*"
+            }]
+        });
+        expect(settings).not.undefined;
+        const data = settings.constructConfigurationObject({ separator: "/" });
+        expect(data).not.undefined;
+        expect(data.app.settings.fontColor).eq("red");
+        expect(data.app.settings.fontSize).eq("40");
+    });
+
+    it("should throw error when construct configuration object with invalid separator", async () => {
+        const connectionString = createMockedConnectionString();
+        const settings = await load(connectionString, {
+            selectors: [{
+                keyFilter: "app%settings%*"
+            }]
+        });
+        expect(settings).not.undefined;
+
+        expect(() => {
+            // Below line will throw error because of type checking, i.e. Type '"%"' is not assignable to type '"/" | "." | "," | ";" | "-" | "_" | "__" | ":" | undefined'.ts(2322)
+            // Here force to turn if off for testing purpose, as JavaScript does not have type checking.
+            // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+            // @ts-ignore
+            settings.constructConfigurationObject({ separator: "%" });
+        }).to.throw("Invalid separator '%'. Supported values: '.', ',', ';', '-', '_', '__', '/', ':'.");
+    });
 });