You seem to referring to "Test Bias" with your statement about white people suppressing blacks then unfairly testing them at the drop of a hat.
“Test Bias”
At this point, the egalitarian defense claims that IQ tests are somehow biased against blacks. Common as this charge is, it is nothing more than an ex post facto explanation for results that displease the egalitarians, for no one can look through a well-designed intelligence test and explain what the bias is and where it is to be found.
In fact, many modern IQ tests, such as Raven’s Progressive Matrices, have no verbal or cultural content at all. They test a person’s understanding of shapes and patterns, and are routinely given to people who do not even speak English. Other varieties of IQ test do involve language and inevitably have some cultural content — and these are the very tests on which the black/white gap in scores is narrowest. The more culturally specific an intelligence test is, the narrower the black/white gap becomes. The most abstract, culture-free tests show the largest gap.
The theory of “test bias” is that unfair tests consistently underrate blacks’ abilities. If that were true, blacks who got the same test scores as whites would do better than the whites at the things test scores are supposed to measure: they would get better grades and do their jobs better. This does not happen; blacks do no better than the test scores predict. This raises a larger and different issue. Both the tests and the abilities they are supposed to measure may be biased against blacks. Some egalitarians actually make this argument, but it comes dangerously close to arguing that ability and intelligence themselves are somehow biased against blacks.
The “cultural bias” position is further weakened by the fact that newly-arrived Asian immigrants, for whom the United States really is an alien culture, outperform both blacks and whites on IQ tests. The assertion that the same tests that are culturally biased against blacks somehow favor Asians strains credibility.
If blacks are as intelligent as whites, there must be some way to demonstrate this. None has ever been devised. Are we to conclude that the intelligence of blacks remains forever hidden because every method for measuring it is faulty? Believers in test bias cannot explain why it is impossible to design an intelligence test — carefully eliminating all bias — on which blacks score as well as whites. The explanation is that there is no bias to eliminate. “Bias” is an imaginary culprit.