VisualizerTest: Add tests for visualizer effect parameters

Bug: 305866207

Test: atest VtsHalVisualizerTargetTest

Change-Id: I07faeabe1fc468fb0ba480266ba68e8882c3801e
diff --git a/audio/aidl/vts/EffectHelper.h b/audio/aidl/vts/EffectHelper.h
index 0fa170f..3877c60 100644
--- a/audio/aidl/vts/EffectHelper.h
+++ b/audio/aidl/vts/EffectHelper.h
@@ -83,6 +83,8 @@
     return prefix;
 }
 
+static constexpr float kMaxAudioSampleValue = 1;
+
 class EffectHelper {
   public:
     void create(std::shared_ptr<IFactory> factory, std::shared_ptr<IEffect>& effect,
@@ -413,6 +415,19 @@
         }
     }
 
+    // Fill inputBuffer with random values between -maxAudioSampleValue to maxAudioSampleValue
+    void generateInputBuffer(std::vector<float>& inputBuffer, size_t startPosition, bool isStrip,
+                             size_t channelCount,
+                             float maxAudioSampleValue = kMaxAudioSampleValue) {
+        size_t increment = isStrip ? 1 /*Fill input at all the channels*/
+                                   : channelCount /*Fill input at only one channel*/;
+
+        for (size_t i = startPosition; i < inputBuffer.size(); i += increment) {
+            inputBuffer[i] =
+                    ((static_cast<float>(std::rand()) / RAND_MAX) * 2 - 1) * maxAudioSampleValue;
+        }
+    }
+
     // Generate multitone input between -1 to +1 using testFrequencies
     void generateMultiTone(const std::vector<int>& testFrequencies, std::vector<float>& input,
                            const int samplingFrequency) {