feat(core): validate that outputs is an array of strings

packages/nx/src/tasks-runner/utils.spec.ts

@@ -489,4 +489,24 @@ describe('utils', () => {
       });
     });
   });
+
+  describe('validateOutputs', () => {
+    it('returns undefined if there are no errors', () => {
+      expect(validateOutputs(['{projectRoot}/dist'])).toBeUndefined();
+    });
+
+    it('throws an error if the output is not an array', () => {
+      expect(() => validateOutputs('output' as unknown as string[])).toThrow(
+        "The 'outputs' field must be an array"
+      );
+    });
+
+    it("throws an error if the output has entries that aren't strings", () => {
+      expect(() =>
+        validateOutputs(['foo', 1, null, true, {}, []] as unknown as string[])
+      ).toThrow(
+        "The 'outputs' field must contain only strings, but received types: [string, number, object, boolean, object, object]"
+      );
+    });
+  });
 });

packages/nx/src/tasks-runner/utils.ts

@@ -107,7 +107,32 @@ class InvalidOutputsError extends Error {
   }
 }
 
+function assertOutputsAreValidType(outputs: unknown) {
+  if (!Array.isArray(outputs)) {
+    throw new Error("The 'outputs' field must be an array");
+  }
+
+  const typesArray = [];
+  let hasInvalidType = false;
+  for (const output of outputs) {
+    if (typeof output !== 'string') {
+      hasInvalidType = true;
+    }
+    typesArray.push(typeof output);
+  }
+
+  if (hasInvalidType) {
+    throw new Error(
+      `The 'outputs' field must contain only strings, but received types: [${typesArray.join(
+        ', '
+      )}]`
+    );
+  }
+}
+
 export function validateOutputs(outputs: string[]) {
+  assertOutputsAreValidType(outputs);
+
   const invalidOutputs = new Set<string>();
 
   for (const output of outputs) {