ci: refactor julia tests, from 5 to 4 (~5 min saved)

Author: consideRatio

repo2docker/buildpacks/julia/julia_project.py

@@ -50,6 +50,16 @@ def julia_version(self):
             compat = project_toml["compat"]["julia"]
         except:
             # Default version which needs to be manually updated with new major.minor releases
+            #
+            # NOTE: Updates to the default version should go hand in hand with
+            #       updates to tests/julia/project/verify where is intent to
+            #       test the version.
+            #
+            # FIXME: When compat = "1.6" is set below and passed to
+            #        find_semver_match, we get 1.8.2 as of 2022-10-09. We should
+            #        clarify the desired behavior and have a unit test of
+            #        find_semver_match to validate it.
+            #
             compat = "1.6"
 
         match = find_semver_match(compat, self.all_julias)

tests/julia/julia_version-1.0.2/README.rst

@@ -0,0 +1,4 @@
+Julia - Project.toml
+--------------------
+
+Test a Project.toml file with a specified version for julia.

tests/julia/julia_version-default/README.rst

@@ -1,6 +1,7 @@
 #!/usr/bin/env julia
-# Verify the version:
+
 if VERSION != v"1.0.2"
+    println("Julia version should be 1.0.2")
     exit(1)
 end