How to use bash inside a Makefile?

Question

bash

I'm trying to write a test section:

BINNAME = passgen
BIN_DIR = ./bin

...
test:
  make
  @len=$($(BIN_DIR)/$(BINNAME) -l20 -ds | wc -m)
  @[ $$len -eq '21' ] && echo "[PASSGEN TEST] OK" || echo "[PASSGEN TEST] ERROR"

If you run the commands directly in the console, then everything is OK.
And now he writes:

$ make test
/bin/bash: строка 0: [: -eq: ожидается использование унарного оператора
[PASSGEN TEST] ERROR

Answer 1

Solved the problem like this:

test:
  make
  @test $$($(BINDIR)/$(BINNAME) -l20 -ds | wc -m) == '21' && echo "[PASSGEN TEST] OK" || echo "[PASSGEN TEST] ERROR"

Answer 2

Solution for the original question: add the line
SHELL = /bin/bash to the Makefile