diff --git a/libs/language-server/src/lib/validation/checks/block-definition.spec.ts b/libs/language-server/src/lib/validation/checks/block-definition.spec.ts
deleted file mode 100644
index e4228a6f4..000000000
--- a/libs/language-server/src/lib/validation/checks/block-definition.spec.ts
+++ /dev/null
@@ -1,86 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Friedrich-Alexander-Universitat Erlangen-Nurnberg
-//
-// SPDX-License-Identifier: AGPL-3.0-only
-
-import { AstNode, AstNodeLocator, LangiumDocument } from 'langium';
-import { NodeFileSystem } from 'langium/node';
-
-import {
-  BlockDefinition,
-  ValidationContext,
-  createJayveeServices,
-} from '../..';
-import {
-  ParseHelperOptions,
-  expectNoParserAndLexerErrors,
-  parseHelper,
-  readJvTestAssetHelper,
-  validationAcceptorMockImpl,
-} from '../../../test';
-
-import { validateBlockDefinition } from './block-definition';
-
-describe('Validation of BlockDefinition', () => {
-  let parse: (
-    input: string,
-    options?: ParseHelperOptions,
-  ) => Promise<LangiumDocument<AstNode>>;
-
-  const validationAcceptorMock = jest.fn(validationAcceptorMockImpl);
-
-  let locator: AstNodeLocator;
-
-  const readJvTestAsset = readJvTestAssetHelper(
-    __dirname,
-    '../../../test/assets/',
-  );
-
-  async function parseAndValidateBlock(input: string) {
-    const document = await parse(input);
-    expectNoParserAndLexerErrors(document);
-
-    const block = locator.getAstNode<BlockDefinition>(
-      document.parseResult.value,
-      'pipelines@0/blocks@0',
-    ) as BlockDefinition;
-
-    validateBlockDefinition(
-      block,
-      new ValidationContext(validationAcceptorMock),
-    );
-  }
-
-  beforeAll(() => {
-    // Create language services
-    const services = createJayveeServices(NodeFileSystem).Jayvee;
-    locator = services.workspace.AstNodeLocator;
-    // Parse function for Jayvee (without validation)
-    parse = parseHelper(services);
-  });
-
-  afterEach(() => {
-    // Reset mock
-    validationAcceptorMock.mockReset();
-  });
-
-  it('should diagnose error on block without pipe', async () => {
-    const text = readJvTestAsset('block-definition/invalid-missing-pipe.jv');
-
-    await parseAndValidateBlock(text);
-
-    expect(validationAcceptorMock).toHaveBeenCalledTimes(1);
-    expect(validationAcceptorMock).toHaveBeenCalledWith(
-      'warning',
-      'A pipe should be connected to the output of this block',
-      expect.any(Object),
-    );
-  });
-
-  it('should have no error on valid block definition', async () => {
-    const text = readJvTestAsset('block-definition/valid-block-definition.jv');
-
-    await parseAndValidateBlock(text);
-
-    expect(validationAcceptorMock).toHaveBeenCalledTimes(0);
-  });
-});
diff --git a/libs/language-server/src/lib/validation/checks/composite-blocktype-definition.spec.ts b/libs/language-server/src/lib/validation/checks/composite-blocktype-definition.spec.ts
index 302f44335..5f719bd85 100644
--- a/libs/language-server/src/lib/validation/checks/composite-blocktype-definition.spec.ts
+++ b/libs/language-server/src/lib/validation/checks/composite-blocktype-definition.spec.ts
@@ -138,4 +138,24 @@ describe('Validation of CompositeBlocktypeDefinition', () => {
       expect.any(Object),
     );
   });
+
+  it('should diagnose error on block without pipe', async () => {
+    const text = readJvTestAsset(
+      'composite-blocktype-definition/invalid-unconnected-block.jv',
+    );
+
+    await parseAndValidateBlocktype(text);
+
+    expect(validationAcceptorMock).toHaveBeenCalledTimes(2);
+    expect(validationAcceptorMock).toHaveBeenCalledWith(
+      'warning',
+      'A pipe should be connected to the input of this block',
+      expect.any(Object),
+    );
+    expect(validationAcceptorMock).toHaveBeenCalledWith(
+      'warning',
+      'A pipe should be connected to the output of this block',
+      expect.any(Object),
+    );
+  });
 });
diff --git a/libs/language-server/src/lib/validation/checks/pipeline-definition.spec.ts b/libs/language-server/src/lib/validation/checks/pipeline-definition.spec.ts
index 0626d2baf..5988ad1e7 100644
--- a/libs/language-server/src/lib/validation/checks/pipeline-definition.spec.ts
+++ b/libs/language-server/src/lib/validation/checks/pipeline-definition.spec.ts
@@ -85,7 +85,7 @@ describe('Validation of PipelineDefinition', () => {
 
     await parseAndValidatePipeline(text);
 
-    expect(validationAcceptorMock).toHaveBeenCalledTimes(1);
+    expect(validationAcceptorMock).toHaveBeenCalledTimes(2); // one warning for unused blocks
     expect(validationAcceptorMock).toHaveBeenCalledWith(
       'error',
       `An extractor block is required for this pipeline`,
@@ -116,4 +116,17 @@ describe('Validation of PipelineDefinition', () => {
       expect.any(Object),
     );
   });
+
+  it('should diagnose error on block without pipe', async () => {
+    const text = readJvTestAsset('pipeline-definition/invalid-missing-pipe.jv');
+
+    await parseAndValidatePipeline(text);
+
+    expect(validationAcceptorMock).toHaveBeenCalledTimes(2); // one error since missing extractor
+    expect(validationAcceptorMock).toHaveBeenCalledWith(
+      'warning',
+      'A pipe should be connected to the output of this block',
+      expect.any(Object),
+    );
+  });
 });
diff --git a/libs/language-server/src/test/assets/block-definition/valid-block-definition.jv b/libs/language-server/src/test/assets/block-definition/valid-block-definition.jv
deleted file mode 100644
index 272e0f9f7..000000000
--- a/libs/language-server/src/test/assets/block-definition/valid-block-definition.jv
+++ /dev/null
@@ -1,23 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Friedrich-Alexander-Universitat Erlangen-Nurnberg
-//
-// SPDX-License-Identifier: AGPL-3.0-only
-
-pipeline Pipeline {
-  block TestExtractor oftype TestFileExtractor {
-  }
-
-  block TestLoader oftype TestTableLoader {
-  }
-
-  TestExtractor -> TestLoader;
-}
-
-builtin blocktype TestFileExtractor {
-  input inPort oftype None;
-  output outPort oftype File;
-}
-
-builtin blocktype TestTableLoader {
-  input inPort oftype File;
-  output outPort oftype None;
-}
\ No newline at end of file
diff --git a/libs/language-server/src/test/assets/composite-blocktype-definition/invalid-unconnected-block.jv b/libs/language-server/src/test/assets/composite-blocktype-definition/invalid-unconnected-block.jv
new file mode 100644
index 000000000..252667e32
--- /dev/null
+++ b/libs/language-server/src/test/assets/composite-blocktype-definition/invalid-unconnected-block.jv
@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2023 Friedrich-Alexander-Universitat Erlangen-Nurnberg
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+composite blocktype TestBlockType {
+  input inPort oftype Table;
+  output outPort oftype File;
+
+  block TestExtractor1 oftype TestFileExtractor { }
+  block TestExtractor2 oftype TestFileExtractor { }
+
+  inPort -> TestExtractor1 -> outPort;
+}
+
+builtin blocktype TestFileExtractor {
+  input inPort oftype Table;
+  output outPort oftype File;
+}
diff --git a/libs/language-server/src/test/assets/block-definition/invalid-missing-pipe.jv b/libs/language-server/src/test/assets/pipeline-definition/invalid-missing-pipe.jv
similarity index 100%
rename from libs/language-server/src/test/assets/block-definition/invalid-missing-pipe.jv
rename to libs/language-server/src/test/assets/pipeline-definition/invalid-missing-pipe.jv