Testnamefornow

Testnamefornow, whose proper name is over 9 million characters long, is an esolang designed to output valid programs in itself that are longer than the source code (usually).

Goals

1. Output valid code for itself but longer, usually.
2. If the output is fed into the code repetitively, it will grow exponentially usually.

Instructions

0 mod 4 - a - Output the source code
1 mod 4 - b - Instead of running the next instruction, output it exactly as it is
2 mod 4 - c - Output the portion of the source code before this point
3 mod 4 - d - Take the length of the source code mod 4 and output that as a letter

Simple output compression and help with understanding

This only applies when displaying an output, not when running it back through the interpreter.

If a letter repeats, do l*n where l is the letter and n is the number of repetitions.

If a group of letters repeat, to (abc)*n where abc is the group of letters and n is the number of repititions.

If b is before a letter, wrap b and the letter in square brackets.

Hello World

bHbeblblbob bWbobrblbd

Simple infinite growth

aa
aaaa
a*16
a*256
a*65536

c-based quine

ccc
ccc
ccc
...

c-based infinite growth

cccc
cccccc
ccccccccccccccc
c*105
c*5460
c*14903070
c*111050740260915
c*6166133456248548335768188155
c*19010600900133834176644234577571914951562754277857057935

ddcd

ddcd
aadda
aaddaaaddabbaadda
aaddaaaddabbaaddaaaddaaaddabbaaddabbaaddaaaddabbaaddaaaddaaaddabbaaddaaaddaaaddabbaaddabbaaddaaaddabbaaddabaaddaaaddabbaaddaaaddaaaddabbaaddabbaaddaaaddabbaadda
(12,000+ characters long)

ddcdcdcd

ddcdcdcd
aaddaddcdaddcdcda
aaddaddcdaddcdcdaaaddaddcdaddcdcdabbaaddaddcdaddcdcdabbaaddaddbaaddaddcdaddcdcdabbaaddaddcdaddbaaddaddcdaddcdbaaddaddcdaddcdcda
(5,400+ characters long)
(9,000,000+ characters long, also the name of this language)