Add tests for ResultSlicer

Signed-off-by: Levko Kravets <[email protected]>

tests/unit/result/ResultSlicer.test.js

@@ -0,0 +1,92 @@
+const { expect } = require('chai');
+const sinon = require('sinon');
+const ResultSlicer = require('../../../dist/result/ResultSlicer').default;
+
+class ResultsProviderMock {
+  constructor(chunks) {
+    this.chunks = chunks;
+  }
+
+  async hasMore() {
+    return this.chunks.length > 0;
+  }
+
+  async fetchNext() {
+    return this.chunks.shift() ?? [];
+  }
+}
+
+describe('ResultSlicer', () => {
+  it('should return chunks of requested size', async () => {
+    const provider = new ResultsProviderMock([
+      [10, 11, 12, 13, 14, 15],
+      [20, 21, 22, 23, 24, 25],
+      [30, 31, 32, 33, 34, 35],
+    ]);
+
+    const slicer = new ResultSlicer({}, provider);
+
+    const chunk1 = await slicer.fetchNext({ limit: 4 });
+    expect(chunk1).to.deep.eq([10, 11, 12, 13]);
+    expect(await slicer.hasMore()).to.be.true;
+
+    const chunk2 = await slicer.fetchNext({ limit: 10 });
+    expect(chunk2).to.deep.eq([14, 15, 20, 21, 22, 23, 24, 25, 30, 31]);
+    expect(await slicer.hasMore()).to.be.true;
+
+    const chunk3 = await slicer.fetchNext({ limit: 10 });
+    expect(chunk3).to.deep.eq([32, 33, 34, 35]);
+    expect(await slicer.hasMore()).to.be.false;
+  });
+
+  it('should return raw chunks', async () => {
+    const provider = new ResultsProviderMock([
+      [10, 11, 12, 13, 14, 15],
+      [20, 21, 22, 23, 24, 25],
+      [30, 31, 32, 33, 34, 35],
+    ]);
+    sinon.spy(provider, 'fetchNext');
+
+    const slicer = new ResultSlicer({}, provider);
+
+    const chunk1 = await slicer.fetchNext({ limit: 4, disableBuffering: true });
+    expect(chunk1).to.deep.eq([10, 11, 12, 13, 14, 15]);
+    expect(await slicer.hasMore()).to.be.true;
+    expect(provider.fetchNext.callCount).to.be.equal(1);
+
+    const chunk2 = await slicer.fetchNext({ limit: 10, disableBuffering: true });
+    expect(chunk2).to.deep.eq([20, 21, 22, 23, 24, 25]);
+    expect(await slicer.hasMore()).to.be.true;
+    expect(provider.fetchNext.callCount).to.be.equal(2);
+  });
+
+  it('should switch between returning sliced and raw chunks', async () => {
+    const provider = new ResultsProviderMock([
+      [10, 11, 12, 13, 14, 15],
+      [20, 21, 22, 23, 24, 25],
+      [30, 31, 32, 33, 34, 35],
+    ]);
+
+    const slicer = new ResultSlicer({}, provider);
+
+    const chunk1 = await slicer.fetchNext({ limit: 4 });
+    expect(chunk1).to.deep.eq([10, 11, 12, 13]);
+    expect(await slicer.hasMore()).to.be.true;
+
+    const chunk2 = await slicer.fetchNext({ limit: 10, disableBuffering: true });
+    expect(chunk2).to.deep.eq([14, 15]);
+    expect(await slicer.hasMore()).to.be.true;
+
+    const chunk3 = await slicer.fetchNext({ limit: 10, disableBuffering: true });
+    expect(chunk3).to.deep.eq([20, 21, 22, 23, 24, 25]);
+    expect(await slicer.hasMore()).to.be.true;
+
+    const chunk4 = await slicer.fetchNext({ limit: 4 });
+    expect(chunk4).to.deep.eq([30, 31, 32, 33]);
+    expect(await slicer.hasMore()).to.be.true;
+
+    const chunk5 = await slicer.fetchNext({ limit: 4 });
+    expect(chunk5).to.deep.eq([34, 35]);
+    expect(await slicer.hasMore()).to.be.false;
+  });
+});