cros: Added a fake fingerprint storage class.

chromeos/dbus/biod/fake_biod_client.h

Index: chromeos/dbus/biod/fake_biod_client.h
diff --git a/chromeos/dbus/biod/fake_biod_client.h b/chromeos/dbus/biod/fake_biod_client.h
index e4fd8410ce8f81f8ca952890d82e4a988af9cea6..b6c0be0a961db554ddf5a0e7e1848c702e37f5bd 100644
--- a/chromeos/dbus/biod/fake_biod_client.h
+++ b/chromeos/dbus/biod/fake_biod_client.h
@@ -5,6 +5,9 @@
 #ifndef CHROMEOS_DBUS_BIOD_FAKE_BIOD_CLIENT_H_
 #define CHROMEOS_DBUS_BIOD_FAKE_BIOD_CLIENT_H_
 
+#include <map>
+#include <string>
+
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "chromeos/chromeos_export.h"
@@ -17,17 +20,41 @@ class ObjectPath;
 
 namespace chromeos {
 
-// A fake implementation of BiodClient.
+class FakeBiodClientTest;
+
+// A fake implementation of BiodClient. It emulates the real Biod daemon by
+// providing the same API and storaging fingerprints locally. A fingerprint is

[Daniel Erat, 2017/04/07 18:27:56]

nit: storing

[sammiequon, 2017/04/07 20:45:50]

Done.

+// represented by a string. During enrollment, fake enrollments are sent as
+// chars. If they are successful they get appended to the current fingerprint,
+// until and compeleted enroll scan is sent. An attempt scan is also sent with a

[Daniel Erat, 2017/04/07 18:27:56]

nit: "until a completed enroll ..."

[sammiequon, 2017/04/07 20:45:50]

Done.

+// char. If that char matches any char in the stored fingerprint string, it is
+// considered a match.
 class CHROMEOS_EXPORT FakeBiodClient : public BiodClient {
  public:
+  // The current session of fingerprint storage. The session determines which
+  // events will be sent from user finger touches.
+  enum class FingerprintSession {
+    NONE = 0,

[Daniel Erat, 2017/04/07 18:27:56]

you don't need the '= 0' here

[sammiequon, 2017/04/07 20:45:50]

Done.

+    ENROLL,
+    AUTH,
+  };
+
   FakeBiodClient();
   ~FakeBiodClient() override;
 
   // Emulates the biod daemon by sending events which the daemon normally sends.
   // Notifies |observers_| about various events. These will be used in tests.
-  void SendEnrollScanDone(biod::ScanResult type_result, bool is_complete);
-  void SendAuthScanDone(biod::ScanResult type_result,
-                        const AuthScanMatches& matches);
+
+  // Emulates a scan that occurs during enrolling a new fingerprint.
+  // |fingerprint| is the fake data of the finger as a char. If |is_complete| is

[Daniel Erat, 2017/04/07 18:27:56]

this char/string interface seems a bit odd. why not just add each scan as a
string, stick them all in a vector, and iterate through them for auth?

[sammiequon, 2017/04/07 20:45:50]

I could do that, but I am wondering why the vector of strings is preferred. Is
the fingerprint as a bunch of chars confusing? Or would you rather each scan be
more specific (ie. "Sammie's first scan")? (Or neither?)

[Daniel Erat, 2017/04/07 20:57:25]

yes, my main thought was that strings are much nicer when it comes to debugging.
they're easier to print in c++. it's easier to come up with descriptive, unique
strings in tests; if you're using 'a', 'b', etc., it's likely that people will
mess up at some point and add a character that's already being used.

[sammiequon, 2017/04/07 22:43:55]

Acknowledged.

+  // true the enroll session is finished, and the record is stored.
+  void SendEnrollScanDone(char fingerprint,
+                          biod::ScanResult type_result,
+                          bool is_complete);
+  // Emulates a scan that occurs during a authentication session. |fingerprint|
+  // is a char which represents the finger, and will be compared with all the
+  // stored fingerprints.
+  void SendAuthScanDone(char fingerprint, biod::ScanResult type_result);
   void SendSessionFailed();
 
   // BiodClient:
@@ -52,7 +79,37 @@ class CHROMEOS_EXPORT FakeBiodClient : public BiodClient {
   void RequestRecordLabel(const dbus::ObjectPath& record_path,
                           const LabelCallback& callback) override;
 
+  // Clears and stored and current records from the fake storage.

[Daniel Erat, 2017/04/07 18:27:56]

s/and/all/

[sammiequon, 2017/04/07 20:45:50]

Done.

+  void Reset();
+
  private:
+  friend FakeBiodClientTest;
+
+  // FakeRecord is the definition of a fake stored fingerprint template.
+  struct FakeRecord {
+    std::string user_id;
+    std::string label;
+    // A fake fingerprint is a string which consists of all the chars which were
+    // "pressed" during the enroll session.
+    std::string fake_fingerprint;
+  };
+
+  // The stored fingerprints.
+  std::map<dbus::ObjectPath, std::unique_ptr<FakeRecord>> records_;
+
+  // Current record in process of getting enrolled and its path. These are
+  // assigned at the start of an enroll session and freed when the enroll
+  // session is finished or cancelled.
+  std::unique_ptr<dbus::ObjectPath> current_record_path_;

[Daniel Erat, 2017/04/07 18:27:56]

you don't need unique_ptr; just use an empty path when it's unset

[sammiequon, 2017/04/07 20:45:50]

Done.

+  std::unique_ptr<FakeRecord> current_record_;
+
+  // Unique indentifier that gets updated each time an enroll session is started
+  // to ensure each record is stored at a different path.
+  int next_record_unique_id_ = 1;
+
+  // The current session of the fake storage.
+  FingerprintSession current_session_ = FingerprintSession::NONE;
+
   base::ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeBiodClient);