Avoid use of 'assert' in unit tests

A failing 'assert' aborts the execution of the test suite,
instead of simply failing the erroneous test, and continuing with other tests.

Change-Id: I3fdaf20a22ea343ac75be7883addbe6ba1e55da1

test/av1_inv_txfm1d_test.cc

@@ -63,7 +63,7 @@ TEST(av1_inv_txfm1d, round_trip) {
         int32_t output[64];
         int32_t round_trip_output[64];
 
-        assert(txfm_size <= NELEMENTS(input));
+        ASSERT_LE(txfm_size, NELEMENTS(input));
 
         for (int ni = 0; ni < txfm_size; ++ni) {
           input[ni] = rnd.Rand16() % input_base - rnd.Rand16() % input_base;

test/av1_inv_txfm2d_test.cc

@@ -56,7 +56,7 @@ class AV1InvTxfm2d : public ::testing::TestWithParam<AV1InvTxfm2dParam> {
 
     for (int ci = 0; ci < count; ci++) {
       int16_t expected[64 * 64] = { 0 };
-      assert(txfm2d_size_ < NELEMENTS(expected));
+      ASSERT_LT(txfm2d_size_, NELEMENTS(expected));
 
       for (int ni = 0; ni < txfm2d_size_; ++ni) {
         if (ci == 0) {
@@ -68,11 +68,11 @@ class AV1InvTxfm2d : public ::testing::TestWithParam<AV1InvTxfm2dParam> {
       }
 
       int32_t coeffs[64 * 64] = { 0 };
-      assert(txfm2d_size_ < NELEMENTS(coeffs));
+      ASSERT_LT(txfm2d_size_, NELEMENTS(coeffs));
       fwd_txfm_func(expected, coeffs, txfm1d_size_, tx_type_, bd);
 
       uint16_t actual[64 * 64] = { 0 };
-      assert(txfm2d_size_ < NELEMENTS(actual));
+      ASSERT_LT(txfm2d_size_, NELEMENTS(actual));
       inv_txfm_func(coeffs, actual, txfm1d_size_, tx_type_, bd);
 
       for (int ni = 0; ni < txfm2d_size_; ++ni) {