Refactor PrinterDiscoverer and PrinterDetector to use a common interface.

chrome/browser/chromeos/printing/combining_printer_detector_unittest.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/chromeos/printing/combining_printer_detector.h"
+
+#include <algorithm>
+#include <memory>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/memory/ptr_util.h"
+#include "base/observer_list.h"
+#include "base/strings/string_util.h"
+#include "chromeos/printing/printer_configuration.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace chromeos {
+
+namespace {
+// Fake printer detectors used as the source of detections to be combined.
+class FakePrinterDetector : public PrinterDetector {
+ public:
+  explicit FakePrinterDetector(
+      const std::vector<std::string>& starting_printers)
+      : printer_ids_(starting_printers.begin(), starting_printers.end()) {}
+
+  ~FakePrinterDetector() override = default;
+
+  void Start() override {}
+
+  // Add these printers to the list of detected printers, and notify
+  // downstream observers.
+  void AddPrinters(const std::vector<std::string>& ids) {
+    for (const std::string& id : ids) {
+      CHECK(printer_ids_.insert(id).second)
+          << "Cowardly refusing to add printer with duplicate id " << id;
+    }
+    Notify();
+  }
+
+  // Remove these printers from the list of detected printers, and notify
+  // downstream observers.
+  void RemovePrinters(const std::vector<std::string>& ids) {
+    for (const std::string id : ids) {
+      CHECK_EQ(printer_ids_.erase(id), static_cast<size_t>(1))
+          << "Can't remove printer with nonexistant id " << id;
+    }
+    Notify();
+  }
+
+  // Tell downstream observers that we're done finding printers.
+  void PrinterScanComplete() {
+    for (PrinterDetector::Observer& observer : observer_list_) {
+      observer.OnPrinterScanComplete();
+    }
+  }
+
+  // PrinterDetector implementations.
+  void AddObserver(PrinterDetector::Observer* observer) override {
+    observer_list_.AddObserver(observer);
+  }
+
+  void RemoveObserver(PrinterDetector::Observer* observer) override {
+    observer_list_.RemoveObserver(observer);
+  }
+
+  std::vector<Printer> GetPrinters() override {
+    std::vector<Printer> printers;
+    for (const std::string& id : printer_ids_) {
+      printers.push_back(Printer(id));
+    }
+    return printers;
+  }
+
+ private:
+  void Notify() {
+    std::vector<Printer> printers = GetPrinters();
+    for (PrinterDetector::Observer& observer : observer_list_) {
+      observer.OnPrintersFound(printers);
+    }
+  }
+
+  base::ObserverList<PrinterDetector::Observer> observer_list_;
+
+  // In the fake, we only use printer ids to figure out if the right printers
+  // are being propagated.  So internally we just track ids and construct
+  // printers on the fly when asked for them.
+  std::set<std::string> printer_ids_;
+};
+
+class PrintingCombiningPrinterDetectorTest : public testing::Test,
+                                             public PrinterDetector::Observer {
+ public:
+  void Init(const std::vector<std::vector<std::string>>& id_lists) {
+    combining_detector_ = CombiningPrinterDetector::Create();
+
+    bool test_owned = false;
+    for (const std::vector<std::string>& id_list : id_lists) {
+      // Divide up fake detectors between owned and unowned to exercise both
+      // paths.  It shouldn't really matter in the test below where ownership of
+      // a specific fake detector lies.
+      auto fake_detector = base::MakeUnique<FakePrinterDetector>(id_list);
+      fake_detectors_.push_back(fake_detector.get());
+      if (test_owned) {
+        combining_detector_->AddDetector(fake_detector.get());
+        owned_fake_detectors_.emplace_back(std::move(fake_detector));
+      } else {
+        combining_detector_->AddOwnedDetector(std::move(fake_detector));
+      }
+      test_owned = !test_owned;
+    }
+    combining_detector_->AddObserver(this);
+    combining_detector_->Start();
+    printers_ = combining_detector_->GetPrinters();
+  }
+
+  void OnPrintersFound(const std::vector<Printer>& printers) override {
+    printers_ = printers;
+  }
+
+  void OnPrinterScanComplete() override { scan_complete_ = true; }
+
+ protected:
+  // Testing utility function -- return true if the printers we got in the most
+  // recent OnPrintersFound call are the same as printers (without considering
+  // order).
+  void ExpectFoundPrintersAre(const std::vector<std::string>& expected_ids) {
+    std::vector<std::string> sorted_expected(expected_ids.begin(),
+                                             expected_ids.end());
+    std::vector<std::string> sorted_actual;
+    for (const Printer& printer : printers_) {
+      sorted_actual.push_back(printer.id());
+    }
+    std::sort(sorted_expected.begin(), sorted_expected.end());
+    std::sort(sorted_actual.begin(), sorted_actual.end());
+    if (sorted_expected != sorted_actual) {
+      ADD_FAILURE() << "Printer ids mismatch.  Expected: {"
+                    << base::JoinString(sorted_expected, ", ") << "}; Found: {"
+                    << base::JoinString(sorted_actual, ", ") << "}";
+    }
+  }
+
+  // Have we been notified that the scan is complete?
+  bool scan_complete_ = false;
+
+  // The printers in the most recent OnPrintersFound call.
+  std::vector<Printer> printers_;
+
+  // The fake detectors plugged into the combining detector.
+  std::vector<FakePrinterDetector*> fake_detectors_;
+
+  // Cleanup pointers for fake detectors owned by the test.  (The
+  // other fake detectors are owned by the combining_detector.
+  std::vector<std::unique_ptr<FakePrinterDetector>> owned_fake_detectors_;
+
+  std::unique_ptr<CombiningPrinterDetector> combining_detector_;
+};
+
+TEST_F(PrintingCombiningPrinterDetectorTest, BasicUsage) {
+  Init({{"1a"}, std::vector<std::string>(), {"3a"}});
+  ExpectFoundPrintersAre({"1a", "3a"});
+  EXPECT_FALSE(scan_complete_);
+
+  // Find some printers in the second detector.
+  fake_detectors_[1]->AddPrinters({"2a", "2b", "2c"});
+  ExpectFoundPrintersAre({"1a", "2a", "2b", "2c", "3a"});
+  EXPECT_FALSE(scan_complete_);
+
+  // Find some printers on the first detector.
+  fake_detectors_[0]->AddPrinters({"1b"});
+  ExpectFoundPrintersAre({"1a", "1b", "2a", "2b", "2c", "3a"});
+  EXPECT_FALSE(scan_complete_);
+
+  // Have the first detector signal completion, the combined detector should
+  // not be complete until all 3 fake detectors have completed.
+  fake_detectors_[0]->PrinterScanComplete();
+  EXPECT_FALSE(scan_complete_);
+  ExpectFoundPrintersAre({"1a", "1b", "2a", "2b", "2c", "3a"});
+
+  // Exercise removal of a printer.
+  fake_detectors_[2]->RemovePrinters({"3a"});
+  EXPECT_FALSE(scan_complete_);
+  ExpectFoundPrintersAre({"1a", "1b", "2a", "2b", "2c"});
+
+  // Mark the 3rd detector as complete.  The 2nd detector has still not declared
+  // itself complete.
+  fake_detectors_[2]->PrinterScanComplete();
+  EXPECT_FALSE(scan_complete_);
+  ExpectFoundPrintersAre({"1a", "1b", "2a", "2b", "2c"});
+
+  // Multiple scan complete calls from the same detector shouldn't happen, but
+  // if they do happen, it should be a nop.
+  fake_detectors_[2]->PrinterScanComplete();
+  EXPECT_FALSE(scan_complete_);
+  ExpectFoundPrintersAre({"1a", "1b", "2a", "2b", "2c"});
+
+  // We can still add printers from a detector that has declared itself
+  // complete.
+  fake_detectors_[0]->AddPrinters({"1c"});
+  ExpectFoundPrintersAre({"1a", "1b", "1c", "2a", "2b", "2c"});
+  EXPECT_FALSE(scan_complete_);
+
+  // Finally the 2nd detector declares itself complete, which should mean the
+  // combined detector is now complete.
+  fake_detectors_[1]->PrinterScanComplete();
+  EXPECT_TRUE(scan_complete_);
+  ExpectFoundPrintersAre({"1a", "1b", "1c", "2a", "2b", "2c"});
+
+  // Should still be able to add printers even after completion.
+  fake_detectors_[2]->AddPrinters({"3g", "3h", "3i"});
+  EXPECT_TRUE(scan_complete_);
+  ExpectFoundPrintersAre(
+      {"1a", "1b", "1c", "2a", "2b", "2c", "3g", "3h", "3i"});
+}
+
+}  // namespace
+}  // namespace chromeos