How To Unit Test PostgreSQL C-Language Functions

I am developing a user defined function for PostgreSQL in C. This function will be used as part of a user defined aggregate. I am following the documentation on User-defined Aggregates and C-Language Funtions. I am aware of the extension building infrastructure that a PostgreSQL installation provides, documented here , which also provides a means of testing the extension. However, to ease the development of PostgreSQL extensions, I was wondering if there is any way to test the user function using regular C unit testing techniques.

I am trying to use CMocka for my unit testing. This is complicated by thePG_FUNCTION_ARGS and PG_FUNCTION_INFO_V1 macros from fmgr.h that are needed for C functions that will be interfacing with PostgreSQL. These macros tend to abstract some of the parameter handling and as a result obfuscate this functionality. As a result, I am having difficulty calling my PostgreSQL user function in a unit test. The errors I am having are related to the expected parameter types. I'm not sure how to manually construct a parameter list via the macros for my function. Below are the GCC errors I get when I try to run my unit test.

    gcc -fprofile-arcs -ftest-coverage -I '/usr/include/postgresql/10/server' ./tests/test_max_pos_min_neg.c -o ./build/tests/test_max_pos_min_neg
./tests/test_max_pos_min_neg.c: In function ‘test_get_max_pos_min_neg’:
./tests/test_max_pos_min_neg.c:21:25: warning: passing argument 1 of ‘get_max_pos_min_neg’ from incompatible pointer type [-Wincompatible-pointer-types]
     get_max_pos_min_neg((float4 *) init_cond, 10.0, -2.5, 7.5);
                         ^
In file included from ./tests/test_max_pos_min_neg.c:6:0:
./tests/../src/max_pos_min_neg.h:8:7: note: expected ‘FunctionCallInfo {aka struct FunctionCallInfoData *}’ but argument is of type ‘float4 * {aka float *}’
 Datum get_max_pos_min_neg(PG_FUNCTION_ARGS);
       ^~~~~~~~~~~~~~~~~~~
./tests/test_max_pos_min_neg.c:21:5: error: too many arguments to function ‘get_max_pos_min_neg’
     get_max_pos_min_neg((float4 *) init_cond, 10.0, -2.5, 7.5);
     ^~~~~~~~~~~~~~~~~~~
In file included from ./tests/test_max_pos_min_neg.c:6:0:
./tests/../src/max_pos_min_neg.h:8:7: note: declared here
 Datum get_max_pos_min_neg(PG_FUNCTION_ARGS);
       ^~~~~~~~~~~~~~~~~~~
./tests/test_max_pos_min_neg.c:24:5: warning: implicit declaration of function ‘assert_float_equal’; did you mean ‘assert_int_equal’? [-Wimplicit-function-declaration]
     assert_float_equal(init_cond[0], 10.0, EPSILON);
     ^~~~~~~~~~~~~~~~~~
     assert_int_equal
Makefile:59: recipe for target 'build/tests/test_max_pos_min_neg' failed
make: *** [build/tests/test_max_pos_min_neg] Error 1

Here is my source code:

#include "postgres.h"
#include "fmgr.h"
#include "utils/array.h"

PG_MODULE_MAGIC;

Datum get_max_pos_min_neg(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(get_max_pos_min_neg);

// Computes the maximum positive and mininum negative sentiment scores.
Datum
get_max_pos_min_neg(PG_FUNCTION_ARGS)
{
    ArrayType *state_array;
    float4 *state;
    float4 pos, neg, score;

    state_array = PG_GETARG_ARRAYTYPE_P(0);
    pos = PG_GETARG_FLOAT4(1);
    neg = PG_GETARG_FLOAT4(2);
    score = PG_GETARG_FLOAT4(3);

    state = (float4 *) ARR_DATA_PTR(state_array);

    if (state[2] < score)
    {
        state[0] = pos;
        state[1] = neg;
        state[2] = score;
    }
    if (score < state[5])
    {
        state[3] = pos;
        state[4] = neg;
        state[5] = score;
    }
    PG_RETURN_ARRAYTYPE_P(state);
}

My header file:

#include "postgres.h"
#include "fmgr.h"
#include "utils/array.h"

Datum get_max_pos_min_neg(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(get_max_pos_min_neg);

My unit test:

#include "../src/max_pos_min_neg.h"
#include <stdarg.h>
#include <stddef.h>
#include <setjmp.h>
#include "cmocka.h"

const float4 EPSILON = 0.001;

void 
test_get_max_pos_min_neg(void **state)
{
    (void) state; /* unused */
    // This is the initial condition used by the SQL stored procedure
    float4 init_cond[] = {0, 0, -1, 0, 0, 100};

    get_max_pos_min_neg(init_cond, 10.0, -2.5, 7.5);

    // init_cond should now be {10.0, -2.5, 7.5, 10.0, -2.5, 7.5}
    assert_float_equal(init_cond[0], 10.0, EPSILON);
    assert_float_equal(init_cond[1], -2.5, EPSILON);
    assert_float_equal(init_cond[2], 7.5, EPSILON);
    assert_float_equal(init_cond[3], 10.0, EPSILON);
    assert_float_equal(init_cond[4], -2.5, EPSILON);
    assert_float_equal(init_cond[5], 7.5, EPSILON);
}

const struct CMUnitTest tests[] = { 
    cmocka_unit_test(test_get_max_pos_min_neg)
};

int 
main(void)
{
    return cmocka_run_group_tests(tests, NULL, NULL);
}

Any help you can provide on how to unit test PostgreSQL C-Language functions outside of PostgreSQL would be much appreciated. Thank you!