2 files changed, 46 insertions, 0 deletions
diff --git a/test/gl_video.c b/test/gl_video.c
new file mode 100644
index 0000000000..543ff2e295
--- /dev/null
+++ b/test/gl_video.c
@@ -0,0 +1,42 @@
+#include "test_helpers.h"
+#include "video/out/gl_video.h"
+
+static void test_scale_ambient_lux_limits(void **state) {
+    float x;
+    x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 16.0);
+    assert_double_equal(x, 2.40f);
+
+    x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 64.0);
+    assert_double_equal(x, 1.961f);
+}
+
+static void test_scale_ambient_lux_sign(void **state) {
+    float x;
+    x = gl_video_scale_ambient_lux(16.0, 64.0, 1.961, 2.40, 64.0);
+    assert_double_equal(x, 2.40f);
+}
+
+static void test_scale_ambient_lux_clamping(void **state) {
+    float x;
+    x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 0.0);
+    assert_double_equal(x, 2.40f);
+}
+
+static void test_scale_ambient_lux_log10_midpoint(void **state) {
+    float x;
+    // 32 corresponds to the the midpoint after converting lux to the log10 scale
+    x = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, 32.0);
+    float mid_gamma = (2.40 - 1.961) / 2 + 1.961;
+    assert_double_equal(x, mid_gamma);
+}
+
+int main(void) {
+    const UnitTest tests[] = {
+        unit_test(test_scale_ambient_lux_limits),
+        unit_test(test_scale_ambient_lux_sign),
+        unit_test(test_scale_ambient_lux_clamping),
+        unit_test(test_scale_ambient_lux_log10_midpoint),
+    };
+    return run_tests(tests);
+}
+
diff --git a/test/test_helpers.h b/test/test_helpers.h
index 3dfe08fdbe..7a61da82ea 100644
--- a/test/test_helpers.h
+++ b/test/test_helpers.h
@@ -7,5 +7,9 @@
 #include <cmocka.h>
 
 #include <stdio.h>
+#include <math.h>
+#include <float.h>
+
+#define assert_double_equal(a, b) assert_true(fabs(a - b) <= DBL_EPSILON)
 
 #endif