To execute them just use the tests for the respective day through make dayXX (some days require extra code files, the make instructions contains them):
# make day01
go test -cover -v \
day01.go day01_test.go \
helpers.go intcode.go
=== RUN TestCalculateDay1_Examples
--- PASS: TestCalculateDay1_Examples (0.00s)
=== RUN TestCalculateDay1_Part1
--- PASS: TestCalculateDay1_Part1 (0.00s)
day01_test.go:34: Solution Day 1 Part 1: 3126794
=== RUN TestCalculateDay1_Part2
--- PASS: TestCalculateDay1_Part2 (0.00s)
day01_test.go:43: Solution Day 1 Part 2: 4687331
PASS
coverage: 23.3% of statements
ok command-line-arguments (cached) coverage: 23.3% of statements