diff --git a/src/cache/index.test.ts b/src/cache/index.test.ts
index 8438ab0..78ba118 100644
--- a/src/cache/index.test.ts
+++ b/src/cache/index.test.ts
@@ -38,6 +38,18 @@ describe('Cache Module', () => {
             expect(result).toBeNull()
         })
 
+        it('should return null for internal data sources', async () => {
+            mockDataSource.source = 'internal'
+            const result = await beforeQueryCache({
+                sql: 'SELECT * FROM users',
+                params: [],
+                dataSource: mockDataSource,
+            })
+
+            expect(result).toBeNull()
+            expect(mockDataSource.rpc.executeQuery).not.toHaveBeenCalled()
+        })
+
         it('should return null if query has parameters', async () => {
             const result = await beforeQueryCache({
                 sql: 'SELECT * FROM users WHERE id = ?',
@@ -58,6 +70,18 @@ describe('Cache Module', () => {
             expect(result).toBeNull()
         })
 
+        it('should return null if no cached row is present', async () => {
+            vi.mocked(mockDataSource.rpc.executeQuery).mockResolvedValue([])
+
+            const result = await beforeQueryCache({
+                sql: 'SELECT * FROM users',
+                params: [],
+                dataSource: mockDataSource,
+            })
+
+            expect(result).toBeNull()
+        })
+
         it('should return cached result if present and valid', async () => {
             const cachedData = {
                 timestamp: new Date().toISOString(),
@@ -111,6 +135,19 @@ describe('Cache Module', () => {
             expect(mockDataSource.rpc.executeQuery).not.toHaveBeenCalled()
         })
 
+        it('should not cache internal data source results', async () => {
+            mockDataSource.source = 'internal'
+
+            await afterQueryCache({
+                sql: 'SELECT * FROM users',
+                params: [],
+                result: [{ id: 1, name: 'John' }],
+                dataSource: mockDataSource,
+            })
+
+            expect(mockDataSource.rpc.executeQuery).not.toHaveBeenCalled()
+        })
+
         it('should not cache modifying queries (UPDATE)', async () => {
             await afterQueryCache({
                 sql: 'UPDATE users SET name = "John" WHERE id = 1',
@@ -153,6 +190,30 @@ describe('Cache Module', () => {
                 params: expect.any(Array),
             })
         })
+
+        it('should swallow cache write errors', async () => {
+            const consoleErrorSpy = vi
+                .spyOn(console, 'error')
+                .mockImplementation(() => {})
+            vi.mocked(mockDataSource.rpc.executeQuery).mockRejectedValue(
+                new Error('database unavailable')
+            )
+
+            const result = await afterQueryCache({
+                sql: 'SELECT * FROM users',
+                params: [],
+                result: [{ id: 1, name: 'John' }],
+                dataSource: mockDataSource,
+            })
+
+            expect(result).toBeUndefined()
+            expect(consoleErrorSpy).toHaveBeenCalledWith(
+                'Error in cache operation:',
+                expect.any(Error)
+            )
+
+            consoleErrorSpy.mockRestore()
+        })
     })
 
     describe('hasModifyingStatement', () => {