Rework how are unit test run

Running unit tests from sources was failing with:
./tmt-test-wrapper.sh-default-0-default-0: line 1: cd: too many arguments

Copy over the approach from osbuild repository.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

plans/unit-tests.fmf

@@ -2,5 +2,6 @@ summary: Run unit tests from source
 discover:
     how: fmf
     dist-git-source: true
+    filter: tag:unit-test
 execute:
     how: tmt

tests/unit-tests/main.fmf

@@ -0,0 +1,4 @@
+summary: Run osbuild-composer unit tests from dist-git sources
+tag: unit-test
+duration: 1h
+test: ./run-unit-tests.sh

tests/unit-tests/run-unit-tests.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/bash
+
+set -euxo pipefail
+
+source /etc/os-release
+
+# Move to the checked out git repo with the test plans
+# this should be the root of the dist-git repo
+cd "${TMT_TREE}"
+
+# install all test dependencies
+sudo dnf install -y rpmdevtools
+sudo dnf builddep -y osbuild-composer.spec
+
+# Move to the directory with sources
+cd "${TMT_SOURCE_DIR}"
+
+# Extract the Source0 basename without extension
+SRC_DIR=$(spectool --source 0 osbuild-composer.spec | sed 's/.\+\(osbuild-composer-[0-9]\+\)\.tar\.gz/\1/')
+
+# Move to the extracted sources directory (patches are applied by default)
+cd "${SRC_DIR}"
+
+GOFLAGS="-mod=vendor -tags=exclude_graphdriver_btrfs" go test ./...

tests/unit.fmf

@@ -1,5 +0,0 @@
-summary: Run unit tests
-require:
-  - golang
-test: cd ../osbuild-composer-*/ && sudo dnf builddep -y osbuild-composer.spec && GOFLAGS="-mod=vendor -tags=exclude_graphdriver_btrfs" go test ./...
-duration: 1h