feat: accept empty string in config.resolve.extensions

- remove minLength from extensions in schema/WebpackOptions
- add tests reflecting the change
- no conflicts with existing tests
- no conflicts with enhanced-resolve

schemas/WebpackOptions.json

@@ -3194,8 +3194,7 @@
           "type": "array",
           "items": {
             "description": "Extension added to the request when trying to find the file.",
-            "type": "string",
-            "minLength": 1
+            "type": "string"
           }
         },
         "fallback": {

test/configCases/resolving/extensions-order/a

@@ -0,0 +1 @@
+module.exports = "1";

test/configCases/resolving/extensions-order/a.js

@@ -0,0 +1 @@
+module.exports = "2";

test/configCases/resolving/extensions-order/b

@@ -0,0 +1 @@
+module.exports = "1"

test/configCases/resolving/extensions-order/b.json

@@ -0,0 +1 @@
+{ "b": "2" }

test/configCases/resolving/extensions-order/index.js

@@ -0,0 +1,4 @@
+it("should resolve respecting resolve.extensions order when enforceExtension: true", () => {
+	require("./a");
+	require("./b")
+});

test/configCases/resolving/extensions-order/webpack.config.js

@@ -0,0 +1,23 @@
+module.exports = {
+	resolve: {
+		enforceExtension: true,
+		extensions: [".js", "", ".json"],
+		plugins: [
+			{
+				apply(resolver) {
+					resolver.hooks.result.tap("Test", (request, resolverContext) => {
+						if (/a$|a\.json$/.test(request.path))
+							throw new Error(
+								`Trying to resolve respecting resolve.extensions order ${request.path}`
+							);
+
+						if (/b.json$/.test(request.path))
+							throw new Error(
+								`Trying to resolve respecting resolve.extensions order ${request.path}`
+							);
+					});
+				}
+			}
+		]
+	}
+};