Test: add noise Wave generation testing

Refs: #9

src/generators.cpp

@@ -1,4 +1,6 @@
 #include <cmath>
+#include <random>
+#include "common.h"
 #include "generators.h"
 #include "wave.h"
 
@@ -84,3 +86,18 @@ sample_table_t gen_isaw()
 
   return isaw_vals;
 }
+
+sample_table_t gen_noise()
+{
+  // setup RNG for floats in [-1, 1]
+  std::default_random_engine generator;
+  std::uniform_real_distribution<float_t> distribution(-1, 1);
+  sample_table_t noise_vals = {};
+  // Set first and last value to 0
+  noise_vals[0] = 0;
+  noise_vals[DEFAULT_N_SAMPLES - 1] = 0;
+  for (uint16_t i = 1; i < DEFAULT_N_SAMPLES - 1; i++) {
+    noise_vals[i] = distribution(generator);
+  }
+  return noise_vals;
+}

src/generators.h

@@ -31,4 +31,9 @@ sample_table_t gen_isaw();
  */
 sample_table_t gen_tri();
 
+/*! Generate noise wave data
+    @return a table of values
+ */
+sample_table_t gen_noise();
+
 #endif // GENERATORS_H_

tests/generators_test.cpp

@@ -33,3 +33,13 @@ TEST(Generator, InverseSawWave) {
   // Starts at 1
   EXPECT_EQ(t[0], 1);
 }
+
+TEST(Generator, NoiseWave)
+{
+  sample_table_t t = gen_noise();
+  // Always start and end at 0
+  EXPECT_EQ(t[0], 0);
+  EXPECT_EQ(t[DEFAULT_N_SAMPLES - 1], 0);
+  // Check second value, probably not equal to 0
+  EXPECT_NE(t[1], 0);
+}