Put functional tests in `tests/functional`

I think it is bad for these reasons when `tests/` contains a mix of
functional and integration tests

 - Concepts is harder to understand, the documentation makes a good
   unit vs functional vs integration distinction, but when the
   integration tests are just two subdirs within `tests/` this is not
   clear.

 - Source filtering in the `flake.nix` is more complex. We need to
   filter out some of the dirs from `tests/`, rather than simply pick
   the dirs we want and take all of them. This is a good sign the
   structure of what we are trying to do is not matching the structure
   of the files.

With this change we have a clean:
```shell-session
$ git show 'HEAD:tests'
tree HEAD:tests

functional/
installer/
nixos/
```

(cherry picked from commit 68c81c737571794f7246db53fb4774e94fcf4b7e)

1 files changed, 46 insertions, 0 deletions

diff --git a/tests/functional/search.sh b/tests/functional/search.sh
new file mode 100644
index 000000000..8742f8736
--- /dev/null
+++ b/tests/functional/search.sh
@@ -0,0 +1,46 @@
+source common.sh
+
+clearStore
+clearCache
+
+(( $(nix search -f search.nix '' hello | wc -l) > 0 ))
+
+# Check descriptions are searched
+(( $(nix search -f search.nix '' broken | wc -l) > 0 ))
+
+# Check search that matches nothing
+(( $(nix search -f search.nix '' nosuchpackageexists | wc -l) == 0 ))
+
+# Search for multiple arguments
+(( $(nix search -f search.nix '' hello empty | wc -l) == 2 ))
+
+# Multiple arguments will not exist
+(( $(nix search -f search.nix '' hello broken | wc -l) == 0 ))
+
+## Search expressions
+
+# Check that empty search string matches all
+nix search -f search.nix '' |grepQuiet foo
+nix search -f search.nix '' |grepQuiet bar
+nix search -f search.nix '' |grepQuiet hello
+
+## Tests for multiple regex/match highlighting
+
+e=$'\x1b' # grep doesn't support \e, \033 or even \x1b
+# Multiple overlapping regexes
+(( $(nix search -f search.nix '' 'oo' 'foo' 'oo' | grep -c "$e\[32;1mfoo$e\\[0;1m") == 1 ))
+(( $(nix search -f search.nix '' 'broken b' 'en bar' | grep -c "$e\[32;1mbroken bar$e\\[0m") == 1 ))
+
+# Multiple matches
+# Searching for 'o' should yield the 'o' in 'broken bar', the 'oo' in foo and 'o' in hello
+(( $(nix search -f search.nix '' 'o' | grep -Eoc "$e\[32;1mo{1,2}$e\[(0|0;1)m") == 3 ))
+# Searching for 'b' should yield the 'b' in bar and the two 'b's in 'broken bar'
+# NOTE: This does not work with `grep -c` because it counts the two 'b's in 'broken bar' as one matched line
+(( $(nix search -f search.nix '' 'b' | grep -Eo "$e\[32;1mb$e\[(0|0;1)m" | wc -l) == 3 ))
+
+## Tests for --exclude
+(( $(nix search -f search.nix -e hello | grep -c hello) == 0 ))
+
+(( $(nix search -f search.nix foo --exclude 'foo|bar' | grep -Ec 'foo|bar') == 0 ))
+(( $(nix search -f search.nix foo -e foo --exclude bar | grep -Ec 'foo|bar') == 0 ))
+[[ $(nix search -f search.nix -e bar --json | jq -c 'keys') == '["foo","hello"]' ]]