Add tests

assets/test/lib/history.test.js

@@ -0,0 +1,94 @@
+import History from "../../js/lib/history";
+
+test("goBack returns when there's at least one cell", () => {
+  const history = new History();
+  const expectedEntry = { cellId: "123", line: "1" };
+
+  expect(history.canGoBack()).toBe(false);
+
+  history.entries = [expectedEntry];
+  history.index = 0;
+
+  expect(history.index).toBe(0);
+  expect(history.canGoBack()).toBe(true);
+  expect(history.goBack()).toStrictEqual(expectedEntry);
+});
+
+describe("saveCell", () => {
+  test("does not add duplicated cells", () => {
+    const history = new History();
+    const entry = { cellId: "123", line: "1" };
+
+    expect(history.index).toBe(-1);
+
+    history.entries = [entry];
+    history.index = 0;
+
+    history.saveCell(entry.cellId, entry.line);
+    expect(history.index).toBe(0);
+
+    // It will only add a new cell if the line isn't the same
+    // as the last entry from the stack
+    history.saveCell(entry.cellId, "2");
+    expect(history.index).toBe(1);
+  });
+
+  test("removes oldest entries and keep it with a maximum of 20 entries", () => {
+    const history = new History();
+
+    for (let i = 0; i <= 19; i++) history.saveCell("123", (i + 1).toString());
+
+    expect(history.index).toBe(19);
+
+    history.saveCell("231", "1");
+
+    expect(history.index).toBe(19);
+    expect(history.entries[0]).toStrictEqual({ cellId: "123", line: "2" });
+  });
+
+  test("rewrites the subsequent cells if go back and saves a new cell", () => {
+    const history = new History();
+    expect(history.canGoBack()).toBe(false);
+
+    history.entries = [
+      { cellId: "123", line: "1" },
+      { cellId: "456", line: "1" },
+      { cellId: "789", line: "2" },
+    ];
+    history.index = 2;
+
+    expect(history.canGoBack()).toBe(true);
+
+    // Go back to cell id 456
+    history.goBack();
+    expect(history.index).toBe(1);
+
+    // Go back to cell id 123
+    history.goBack();
+    expect(history.index).toBe(0);
+
+    // Removes the subsequent cells from stack
+    // and adds the cell id 999 to the stack
+    history.saveCell("999", "1");
+    expect(history.index).toBe(1);
+  });
+});
+
+test("removeAllFromCell removes the cells with given id", () => {
+  const history = new History();
+  const cellId = "123456789";
+
+  history.entries = [
+    { cellId: "123", line: "1" },
+    { cellId: "456", line: "1" },
+    { cellId: cellId, line: "1" },
+    { cellId: "1234", line: "1" },
+    { cellId: cellId, line: "1" },
+    { cellId: "8901", line: "1" },
+    { cellId: cellId, line: "1" },
+  ];
+  history.index = 6;
+
+  history.removeAllFromCell(cellId);
+  expect(history.index).toBe(3);
+});