fix: correct regex match condition in SyntaxValidator

packages/imperative/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 All notable changes to the Imperative package will be documented in this file.
 
+## Recent Changes
+
+- BugFix: Fixed a typo in the syntax validation code for positional arguments which caused the validation to never fail. [#2375](https://github.com/zowe/zowe-cli/issues/2375)
 
 ## `8.10.1`
 

packages/imperative/src/cmd/src/syntax/SyntaxValidator.ts

@@ -226,7 +226,7 @@ export class SyntaxValidator {
                 if (!(commandArguments[positional.name] == null)) {
                     if (positional.regex) {
                         if (commandArguments[positional.name]
-                            .toString().match(new RegExp(positional.regex) == null)) {
+                            .toString().match(new RegExp(positional.regex)) == null) {
                             valid = false;
                             this.positionalParameterInvalid(positional,
                                 commandArguments[positional.name], responseObject);

packages/imperative/src/cmd/src/syntax/__tests__/SyntaxValidator.unit.test.ts

@@ -525,6 +525,19 @@ describe("Imperative should provide advanced syntax validation rules", () => {
             expect(svResponse.valid).toEqual(true);
         });
 
+        it("should fail if a positional argument does not match the defined regex", async () => {  
+            const invalidPositional = "invalid_value"; 
+            const regexForPositional = "^[a-zA-Z0-9_]+$";
+
+            return tryOptions.bind(
+                this,
+                `${minValidOptions} ${invalidPositional}`,
+                false,
+                [`Positional argument '${invalidPositional}' does not match the regex: ${regexForPositional}`]
+            )();
+        });
+
+
         describe("We should be able to validate positional arguments of type 'number'", () => {
             const numberCommand: ICommandDefinition = {
                 name: "gimme-number", aliases: [],