1 files changed, 98 insertions, 0 deletions
diff --git a/docshell/test/navigation/browser_test_bfcache_eviction.js b/docshell/test/navigation/browser_test_bfcache_eviction.js
new file mode 100644
index 0000000000..fe0db2742b
--- /dev/null
+++ b/docshell/test/navigation/browser_test_bfcache_eviction.js
@@ -0,0 +1,98 @@
+add_task(async function() {
+  // We don't want the number of total viewers to be calculated by the available size
+  // for this test case. Instead, fix the number of viewers.
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["browser.sessionhistory.max_total_viewers", 3],
+      ["docshell.shistory.testing.bfevict", true],
+      // If Fission is disabled, the pref is no-op.
+      ["fission.bfcacheInParent", true],
+    ],
+  });
+
+  // 1. Open a tab
+  var testPage =
+    "data:text/html,<html id='html1'><body id='body1'>First tab ever opened</body></html>";
+  await BrowserTestUtils.withNewTab({ gBrowser, url: testPage }, async function(
+    browser
+  ) {
+    let testDone = {};
+    if (!SpecialPowers.Services.appinfo.sessionHistoryInParent) {
+      // 2.  Add a promise that will be resolved when the 'content viewer evicted' event goes off
+      testDone.promise = SpecialPowers.spawn(browser, [], async function() {
+        return new Promise(resolve => {
+          let webNavigation = content.docShell.QueryInterface(
+            Ci.nsIWebNavigation
+          );
+          let { legacySHistory } = webNavigation.sessionHistory;
+          // 3. Register a session history listener to listen for a 'content viewer evicted' event.
+          let historyListener = {
+            OnContentViewerEvicted() {
+              ok(
+                true,
+                "History listener got called after a content viewer was evicted"
+              );
+              legacySHistory.removeSHistoryListener(historyListener);
+              // 6. Resolve the promise when we got our 'content viewer evicted' event
+              resolve();
+            },
+            QueryInterface: ChromeUtils.generateQI([
+              "nsISHistoryListener",
+              "nsISupportsWeakReference",
+            ]),
+          };
+          legacySHistory.addSHistoryListener(historyListener);
+          // Keep the weak shistory listener alive
+          content._testListener = historyListener;
+        });
+      });
+    } else {
+      // 2.  Add a promise that will be resolved when the 'content viewer evicted' event goes off
+      testDone.promise = new Promise(resolve => {
+        testDone.resolve = resolve;
+      });
+      let shistory = browser.browsingContext.sessionHistory;
+      // 3. Register a session history listener to listen for a 'content viewer evicted' event.
+      let historyListener = {
+        OnContentViewerEvicted() {
+          ok(
+            true,
+            "History listener got called after a content viewer was evicted"
+          );
+          shistory.removeSHistoryListener(historyListener);
+          delete window._testListener;
+          // 6. Resolve the promise when we got our 'content viewer evicted' event
+          testDone.resolve();
+        },
+        QueryInterface: ChromeUtils.generateQI([
+          "nsISHistoryListener",
+          "nsISupportsWeakReference",
+        ]),
+      };
+      shistory.addSHistoryListener(historyListener);
+      // Keep the weak shistory listener alive
+      window._testListener = historyListener;
+    }
+
+    // 4. Open a second tab
+    testPage = `data:text/html,<html id='html1'><body id='body1'>I am a second tab!</body></html>`;
+    let tab2 = await BrowserTestUtils.openNewForegroundTab(gBrowser, testPage);
+
+    // 5. Navigate the first tab to 4 different pages.
+    // We should get 1 content viewer evicted because it will be outside of the range.
+    // If we have the following pages in our session history: P1 P2 P3 P4 P5
+    // and we are currently at P5, then P1 is outside of the range
+    // (it is more than 3 entries away from current entry) and thus will be evicted.
+    for (var i = 0; i < 4; i++) {
+      testPage = `data:text/html,<html id='html1'><body id='body1'>${i}</body></html>`;
+      let pagePromise = BrowserTestUtils.browserLoaded(browser);
+      BrowserTestUtils.loadURI(browser, testPage);
+      await pagePromise;
+    }
+    // 7. Wait for 'content viewer evicted' event to go off
+    await testDone.promise;
+
+    // 8. Close the second tab
+    BrowserTestUtils.removeTab(tab2);
+  });
+});