In Nechemia 9, we read a recap of God's interaction with Avraham:
אֲשֶׁ֤ר בָּחַ֙רְתָּ֙ בְּאַבְרָ֔ם וְהוֹצֵאת֖וֹ מֵא֣וּר כַּשְׂדִּ֑ים וְשַׂ֥מְתָּ שְּׁמ֖וֹ אַבְרָהָֽם׃
וּמָצָ֣אתָ אֶת־לְבָבוֹ֮ נֶאֱמָ֣ן לְפָנֶיךָ֒ וְכָר֨וֹת עִמּ֜וֹ הַבְּרִ֗ית לָתֵ֡ת אֶת־אֶרֶץ֩...לָתֵ֣ת לְזַרְע֑וֹ
Hashem chose Avram and brought him out of Ur Kasdim and Changed his name to Avraham AND found his heart to be loyal AND established a covenant to give the land...to give it to his descenants
But in Sefer Bereisheet, the last two items seem in different places. The Malbim says that Hashem found Avraham's heart to be loyal after the 10th of the trials ("עד שאחר כל הנסיונות שעמד בהם ונבחן ונמצא לבבו נאמן עם אלהיו") which is in Ber 22.
But the covenant (including using the word "brit") to let Avraham inherit the land and have his descendants inherit the land took place in Ber 12, 13, 15 and 17, before the last 4 tests had been assigned/accomplished. One of those instances is directly after the name change (part of test 6) when Avraham already seems to have been found to be ne'eman/loyal as explained by the Radak on Ber 17:1:
meaning that by fulfillment of this commandment Avram would then be considered as "perfect. Once there would be a visible sign of Avram's faith and loyalty to His Creator on his body this would act at the same time as the symbol of the covenant between G'd and him (and the Jewish people).
What is the Nechemia order adding or trying to teach by placing the events in the order which it does?