STEPS TO REPRODUCE
1. see appended log

OBSERVED RESULT
Running mymoneyfinancialcalculator-test from a MinGW build fails
 
7/38 Test  #8: mymoneyfinancialcalculator-test .......***Failed    0.55 sec

Inspecting the test log  shows:

8: ********* Start testing of MyMoneyFinancialCalculatorTest *********
8: Config: Using QtTest library 5.15.14, Qt 5.15.14 (i386-little_endian-ilp32 shared (dynamic) release build; by GCC 13.2.0), windows 7sp1
8: PASS   : MyMoneyFinancialCalculatorTest::initTestCase()
8: PASS   : MyMoneyFinancialCalculatorTest::testEmptyConstructor()
8: PASS   : MyMoneyFinancialCalculatorTest::testSetPrec()
8: PASS   : MyMoneyFinancialCalculatorTest::testSetNpp()
8: PASS   : MyMoneyFinancialCalculatorTest::testSetPF()
8: PASS   : MyMoneyFinancialCalculatorTest::testSetCF()
8: PASS   : MyMoneyFinancialCalculatorTest::testSetBep()
8: PASS   : MyMoneyFinancialCalculatorTest::testSetDisc()
8: FAIL!  : MyMoneyFinancialCalculatorTest::testSetIr() 'm->d_func()->m_ir == 12.3' returned FALSE. ()
8: /home/abuild/rpmbuild/BUILD/kmymoney-5.1.80+QT515+KF5103+20240819+git.9e9d8d588/kmymoney/mymoney/tests/mymoneyfinancialcalculator-test.cpp(91) : failure location
8: FAIL!  : MyMoneyFinancialCalculatorTest::testSetPv() 'm->d_func()->m_pv == 23.4' returned FALSE. ()
8: /home/abuild/rpmbuild/BUILD/kmymoney-5.1.80+QT515+KF5103+20240819+git.9e9d8d588/kmymoney/mymoney/tests/mymoneyfinancialcalculator-test.cpp(98) : failure location
8: PASS   : MyMoneyFinancialCalculatorTest::testSetPmt()
8: FAIL!  : MyMoneyFinancialCalculatorTest::testSetFv() 'm->d_func()->m_fv == 45.6' returned FALSE. ()
8: /home/abuild/rpmbuild/BUILD/kmymoney-5.1.80+QT515+KF5103+20240819+git.9e9d8d588/kmymoney/mymoney/tests/mymoneyfinancialcalculator-test.cpp(112) : failure location
8: PASS   : MyMoneyFinancialCalculatorTest::testCombinedSet()
8: PASS   : MyMoneyFinancialCalculatorTest::testNumPayments()
8: PASS   : MyMoneyFinancialCalculatorTest::testUseCase1()
8: PASS   : MyMoneyFinancialCalculatorTest::testUseCase2()
8: PASS   : MyMoneyFinancialCalculatorTest::cleanupTestCase()
8: Totals: 14 passed, 3 failed, 0 skipped, 0 blacklisted, 5ms
8: ********* Finished testing of MyMoneyFinancialCalculatorTest *********

EXPECTED RESULT
The test should not fail.

ADDITIONAL INFORMATION
> MyMoneyFinancialCalculatorTest::testSetIr() 'm->d_func()->m_ir == 12.3' 

Both numbers are of type double; the comparison of two values with the operator == may not work due to rounding problems. The use of QCOMPARE(m->d_func()->m_ir, 12.3), can solve this problem, as this type of problem is taken into account.