Testing is the most widely used assessment tool in measuring the development process of students' languagecompetence. Therefore, the existence of valid and reliable language tests appropriate to student achievements in education is of great importance. Research on language test development in foreign language teaching in Kazakhstan is insufficient. The aim ofthis study is to practically demonstrate the basic stages of the test development process and how to conduct content validity analysis with the example of the proficiency test of foreign language (Turkish) prepared by Gazi TÖMER. The research method was based on a quantitative research design. The sample of the research for validation was consisted of 7 experts with experience in Gazi TÖMER. For reliability, there were a total of 66 students studying at Abai KazNPU. The first part of the study was examinedfor the content validity of the relevant test. For this purpose, based on the criteria determined by Webb for the evaluation of learning outcomes, the opinions received from field experts were evaluated using the Lawshe technique. The CVR value of the 45-question test was .96, and the CVI was “significant”. The second part of the study was about reliability. For this purpose, the difficulty level of each item was examined based on the data obtained from the pilot application of the test. Data were analyzedusing Excel and SPSS programs. Additionally, the KR-20 value was calculated and found to be .80, and the test was considered reliable. It is believed that the steps and results included in the study will guide the process of creating valid and reliable tests in various fields.