wishful thinking(illusion that what one would like is true) noun [UK: ˈwɪʃ.fəl ˈθɪŋk.ɪŋ] [US: ˈwɪʃ.fəl ˈθɪŋk.ɪŋ]
一廂情願phrase
don't count your chickens before they're hatched(one should not depend upon a favorable outcome to one's plans until it is certain to occur) phrase [UK: dəʊnt kaʊnt jɔː(r) ˈtʃɪkɪnz bɪ.ˈfɔː(r) ˈðeə(r) hætʃt] [US: ˈdoʊnt ˈkaʊnt ˈjɔːr ˈtʃɪkənz bɪ.ˈfɔːr ˈðer ˈhætʃt]