testimoniare bedeutet auf Englisch

testify [testified, testifying, testifies]▼(to make a declaration, or give evidence, under oath)
verb
[UK: ˈtest.ɪ.faɪ] [US: ˈtest.ə.ˌfaɪ]John testified. = John testimoniò.

witness [witnessed, witnessing, witnesses]▼((transitive) to furnish proof of)
verb
[UK: ˈwɪt.nəs] [US: ˈwɪt.nəs]We have witnesses. = Abbiamo dei testimoni.