diff --git a/public/app/features/explore/utils/set.test.ts b/public/app/features/explore/utils/set.test.ts
new file mode 100644
index 00000000000..4f586814fc7
--- /dev/null
+++ b/public/app/features/explore/utils/set.test.ts
@@ -0,0 +1,52 @@
+import { equal, intersect } from './set';
+
+describe('equal', () => {
+  it('returns false for two sets of differing sizes', () => {
+    const s1 = new Set([1, 2, 3]);
+    const s2 = new Set([4, 5, 6, 7]);
+    expect(equal(s1, s2)).toBe(false);
+  });
+  it('returns false for two sets where one is a subset of the other', () => {
+    const s1 = new Set([1, 2, 3]);
+    const s2 = new Set([1, 2, 3, 4]);
+    expect(equal(s1, s2)).toBe(false);
+  });
+  it('returns false for two sets with uncommon elements', () => {
+    const s1 = new Set([1, 2, 3, 4]);
+    const s2 = new Set([1, 2, 5, 6]);
+    expect(equal(s1, s2)).toBe(false);
+  });
+  it('returns false for two deeply equivalent sets', () => {
+    const s1 = new Set([{ a: 1 }, { b: 2 }, { c: 3 }, { d: 4 }]);
+    const s2 = new Set([{ a: 1 }, { b: 2 }, { c: 3 }, { d: 4 }]);
+    expect(equal(s1, s2)).toBe(false);
+  });
+  it('returns true for two sets with the same elements', () => {
+    const s1 = new Set([1, 2, 3, 4]);
+    const s2 = new Set([4, 3, 2, 1]);
+    expect(equal(s1, s2)).toBe(true);
+  });
+});
+
+describe('intersect', () => {
+  it('returns an empty set for two sets without any common elements', () => {
+    const s1 = new Set([1, 2, 3, 4]);
+    const s2 = new Set([5, 6, 7, 8]);
+    expect(intersect(s1, s2)).toEqual(new Set());
+  });
+  it('returns an empty set for two deeply equivalent sets', () => {
+    const s1 = new Set([{ a: 1 }, { b: 2 }, { c: 3 }, { d: 4 }]);
+    const s2 = new Set([{ a: 1 }, { b: 2 }, { c: 3 }, { d: 4 }]);
+    expect(intersect(s1, s2)).toEqual(new Set());
+  });
+  it('returns a set containing common elements between two sets of the same size', () => {
+    const s1 = new Set([1, 2, 3, 4]);
+    const s2 = new Set([5, 2, 7, 4]);
+    expect(intersect(s1, s2)).toEqual(new Set([2, 4]));
+  });
+  it('returns a set containing common elements between two sets of differing sizes', () => {
+    const s1 = new Set([1, 2, 3, 4]);
+    const s2 = new Set([5, 4, 3, 2, 1]);
+    expect(intersect(s1, s2)).toEqual(new Set([1, 2, 3, 4]));
+  });
+});
diff --git a/public/app/features/explore/utils/set.ts b/public/app/features/explore/utils/set.ts
index a625567ac18..12430384fe4 100644
--- a/public/app/features/explore/utils/set.ts
+++ b/public/app/features/explore/utils/set.ts
@@ -8,27 +8,28 @@ export function equal<T>(a: Set<T>, b: Set<T>): boolean {
   const it = a.values();
   while (true) {
     const { value, done } = it.next();
-    if (b.has(value)) {
-      return false;
-    }
     if (done) {
       return true;
     }
+    if (!b.has(value)) {
+      return false;
+    }
   }
 }
 
 /**
- * Returns the first set with items in the second set through shallow comparison.
+ * Returns a new set with items in both sets using shallow comparison.
  */
 export function intersect<T>(a: Set<T>, b: Set<T>): Set<T> {
+  const result = new Set<T>();
   const it = b.values();
   while (true) {
     const { value, done } = it.next();
-    if (!a.has(value)) {
-      a.delete(value);
-    }
     if (done) {
-      return a;
+      return result;
+    }
+    if (a.has(value)) {
+      result.add(value);
     }
   }
 }