tests: FFT of a constant input

tests/Makefile.am

@@ -8,6 +8,7 @@ check_PROGRAMS = $(TESTS)
 
 test_SOURCES = \
 	test-audio.cc \
+	test-fft.cc \
 	test-utils.cc \
 	test.cc \
 	test.h

tests/test-fft.cc

@@ -0,0 +1,65 @@
+/* test-fft.cc
+ *
+ * Copyright (C) 2013  Alexander Kojevnikov <alexander@kojevnikov.com>
+ *
+ * Spek is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Spek is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Spek.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "spek-fft.h"
+
+#include "test.h"
+
+static void test_const()
+{
+    FFT fft;
+    for (int nbits = 4; nbits < 16; ++nbits) {
+        auto plan = fft.create(nbits);
+        test("input size", 1 << nbits, plan->get_input_size());
+        test("output size", (1 << nbits) / 2 + 1, plan->get_output_size());
+
+        // Test zero input.
+        for (int i = 0; i < plan->get_input_size(); ++i) {
+            plan->set_input(i, 0.0f);
+        }
+        plan->execute();
+        bool ok = true;
+        for (int i = 0; i < plan->get_output_size(); ++i) {
+            if (plan->get_output(i) > -1e12f) {
+                ok = false;
+                break;
+            }
+        }
+        test("zero input", true, ok);
+
+        // Test DC input.
+        for (int i = 0; i < plan->get_input_size(); ++i) {
+            plan->set_input(i, 1.0f);
+        }
+        plan->execute();
+        ok = true;
+        test("dc component", 0.0f, plan->get_output(0));
+        for (int i = 1; i < plan->get_output_size(); ++i) {
+            if (plan->get_output(i) > -1e12f) {
+                ok = false;
+                break;
+            }
+        }
+        test("dc input", true, ok);
+    }
+}
+
+void test_fft()
+{
+    run("fft const", test_const);
+}

tests/test.cc

@@ -26,6 +26,7 @@ int main()
     std::cerr << "-------------" << std::endl;
 
     test_audio();
+    test_fft();
     test_utils();
 
     if (g_passes < g_total) {

tests/test.h

@@ -52,6 +52,7 @@ template<class T> void test(const std::string& message, const T& expected, const
 }
 
 void test_audio();
+void test_fft();
 void test_utils();
 
 #endif