diff --git a/src/lib/core/isConformantState.test.ts b/src/lib/core/isConformantState.test.ts
new file mode 100644
index 0000000..22ad0ac
--- /dev/null
+++ b/src/lib/core/isConformantState.test.ts
@@ -0,0 +1,174 @@
+import { describe, expect, test } from "vitest";
+import { isConformantState } from "./isConformantState.js";
+
+describe("isConformantState", () => {
+    describe("Valid State objects", () => {
+        test("Should return true for minimal valid state with empty hash object.", () => {
+            const state = { hash: {} };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for valid state with hash containing string values.", () => {
+            const state = { hash: { path: "/home", id: "main" } };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for valid state with hash containing mixed value types.", () => {
+            const state = { 
+                hash: { 
+                    path: "/home", 
+                    count: 42, 
+                    active: true,
+                    data: { nested: "value" }
+                } 
+            };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for valid state with additional properties beyond hash.", () => {
+            const state = { 
+                hash: { path: "/home" },
+                extraData: "allowed",
+                metadata: { timestamp: Date.now() }
+            };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for valid state with nested hash object.", () => {
+            const state = { 
+                hash: { 
+                    main: "/home",
+                    sidebar: "/menu",
+                    modal: null,
+                    nested: { deep: { value: "test" } }
+                } 
+            };
+            expect(isConformantState(state)).toBe(true);
+        });
+    });
+
+    describe("Invalid State objects", () => {
+        test("Should return false for null.", () => {
+            expect(isConformantState(null)).toBe(false);
+        });
+
+        test("Should return false for undefined.", () => {
+            expect(isConformantState(undefined)).toBe(false);
+        });
+
+        test("Should return false for primitive string.", () => {
+            expect(isConformantState("not an object")).toBe(false);
+        });
+
+        test("Should return false for primitive number.", () => {
+            expect(isConformantState(42)).toBe(false);
+        });
+
+        test("Should return false for primitive boolean.", () => {
+            expect(isConformantState(true)).toBe(false);
+        });
+
+        test("Should return false for array.", () => {
+            expect(isConformantState([1, 2, 3])).toBe(false);
+        });
+
+        test("Should return false for object without hash property.", () => {
+            const state = { data: "value", path: "/home" };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with null hash.", () => {
+            const state = { hash: null };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with undefined hash.", () => {
+            const state = { hash: undefined };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with string hash.", () => {
+            const state = { hash: "string-value" };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with number hash.", () => {
+            const state = { hash: 42 };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with boolean hash.", () => {
+            const state = { hash: true };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with function hash.", () => {
+            const state = { hash: () => {} };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should return false for object with array hash.", () => {
+            const state = { hash: ["path1", "path2"] };
+            expect(isConformantState(state)).toBe(false);
+        });
+    });
+
+    describe("Edge cases", () => {
+        test("Should return true for empty object with empty hash.", () => {
+            const state = { hash: {} };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for state with Date object in hash.", () => {
+            const state = { hash: { timestamp: new Date() } };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for state with RegExp object in hash.", () => {
+            const state = { hash: { pattern: /test/ } };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return true for state with Error object in hash.", () => {
+            const state = { hash: { error: new Error("test") } };
+            expect(isConformantState(state)).toBe(true);
+        });
+
+        test("Should return false for object with Symbol as hash property key.", () => {
+            const symbolKey = Symbol('hash');
+            const state = { [symbolKey]: {} };
+            expect(isConformantState(state)).toBe(false);
+        });
+
+        test("Should handle circular references in hash object.", () => {
+            const state: any = { hash: {} };
+            state.hash.circular = state.hash;
+            expect(isConformantState(state)).toBe(true);
+        });
+    });
+
+    describe("Type guard behavior", () => {
+        test("Should work as type guard for TypeScript type narrowing.", () => {
+            const unknownValue: unknown = { hash: { path: "/test" } };
+            
+            if (isConformantState(unknownValue)) {
+                // TypeScript should recognize this as State type
+                expect(unknownValue.hash).toBeDefined();
+                expect(typeof unknownValue.hash).toBe('object');
+            } else {
+                throw new Error("Should have passed type guard");
+            }
+        });
+
+        test("Should correctly reject invalid state in type guard context.", () => {
+            const unknownValue: unknown = { data: "not a state" };
+            
+            if (isConformantState(unknownValue)) {
+                throw new Error("Should not have passed type guard");
+            } else {
+                // This path should be taken
+                expect(unknownValue).toBeDefined();
+            }
+        });
+    });
+});
diff --git a/src/lib/core/isConformantState.ts b/src/lib/core/isConformantState.ts
index 08f6ea9..c1bcb4f 100644
--- a/src/lib/core/isConformantState.ts
+++ b/src/lib/core/isConformantState.ts
@@ -13,5 +13,6 @@ export function isConformantState(state: unknown): state is State {
         && state !== null
         && 'hash' in state
         && typeof state.hash === 'object'
-        && state.hash !== null;
+        && state.hash !== null
+        && !Array.isArray(state.hash);
 }