1 files changed, 82 insertions, 0 deletions
diff --git a/docshell/test/navigation/browser_ghistorymaxsize_is_0.js b/docshell/test/navigation/browser_ghistorymaxsize_is_0.js
new file mode 100644
index 0000000000..43c36bbaf2
--- /dev/null
+++ b/docshell/test/navigation/browser_ghistorymaxsize_is_0.js
@@ -0,0 +1,82 @@
+add_task(async function () {
+  // The urls don't really matter as long as they are of the same origin
+  var URL =
+    "http://mochi.test:8888/browser/docshell/test/navigation/bug343515_pg1.html";
+  var URL2 =
+    "http://mochi.test:8888/browser/docshell/test/navigation/bug343515_pg3_1.html";
+
+  // We want to test a specific code path that leads to this call
+  // https://searchfox.org/mozilla-central/rev/e7c61f4a68b974d5fecd216dc7407b631a24eb8f/docshell/base/nsDocShell.cpp#10795
+  // when gHistoryMaxSize is 0 and mIndex and mRequestedIndex are -1
+
+  // 1. Navigate to URL
+  await BrowserTestUtils.withNewTab(
+    { gBrowser, url: URL },
+    async function (browser) {
+      // At this point, we haven't set gHistoryMaxSize to 0, and it is still 50 (default value).
+      if (SpecialPowers.Services.appinfo.sessionHistoryInParent) {
+        let sh = browser.browsingContext.sessionHistory;
+        is(
+          sh.count,
+          1,
+          "We should have entry in session history because we haven't changed gHistoryMaxSize to be 0 yet"
+        );
+        is(
+          sh.index,
+          0,
+          "Shistory's current index should be 0 because we haven't purged history yet"
+        );
+      } else {
+        await ContentTask.spawn(browser, null, () => {
+          var sh = content.window.docShell.QueryInterface(Ci.nsIWebNavigation)
+            .sessionHistory.legacySHistory;
+          is(
+            sh.count,
+            1,
+            "We should have entry in session history because we haven't changed gHistoryMaxSize to be 0 yet"
+          );
+          is(
+            sh.index,
+            0,
+            "Shistory's current index should be 0 because we haven't purged history yet"
+          );
+        });
+      }
+
+      var loadPromise = BrowserTestUtils.browserLoaded(browser, false, URL2);
+      // If we set the pref at the beginning of this page, then when we launch a child process
+      // to navigate to URL in Step 1, because of
+      // https://searchfox.org/mozilla-central/rev/e7c61f4a68b974d5fecd216dc7407b631a24eb8f/docshell/shistory/nsSHistory.cpp#308-312
+      // this pref will be set to the default value (currently 50). Setting this pref after the child process launches
+      // is a robust way to make sure it stays 0
+      await SpecialPowers.pushPrefEnv({
+        set: [["browser.sessionhistory.max_entries", 0]],
+      });
+      // 2. Navigate to URL2
+      // We are navigating to a page with the same origin so that we will stay in the same process
+      BrowserTestUtils.loadURIString(browser, URL2);
+      await loadPromise;
+
+      // 3. Reload the browser with specific flags so that we end up here
+      // https://searchfox.org/mozilla-central/rev/e7c61f4a68b974d5fecd216dc7407b631a24eb8f/docshell/base/nsDocShell.cpp#10795
+      var promise = BrowserTestUtils.browserLoaded(browser);
+      browser.reloadWithFlags(Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_CACHE);
+      await promise;
+
+      if (SpecialPowers.Services.appinfo.sessionHistoryInParent) {
+        let sh = browser.browsingContext.sessionHistory;
+        is(sh.count, 0, "We should not save any entries in session history");
+        is(sh.index, -1);
+        is(sh.requestedIndex, -1);
+      } else {
+        await ContentTask.spawn(browser, null, () => {
+          var sh = content.window.docShell.QueryInterface(Ci.nsIWebNavigation)
+            .sessionHistory.legacySHistory;
+          is(sh.count, 0, "We should not save any entries in session history");
+          is(sh.index, -1);
+          is(sh.requestedIndex, -1);
+        });
+      }
+    }
+  );
+});