Make branch commands work with null refs

3 files changed, 95 insertions, 0 deletions

diff --git a/yarns/branches-workspaces.yarn b/yarns/branches-workspaces.yarn
index 5273f396..f523ebcd 100644
--- a/yarns/branches-workspaces.yarn
+++ b/yarns/branches-workspaces.yarn
@@ -290,3 +290,65 @@ Creating a tag twice should fail.
     WHEN        attempting to tag system branch foo as test123
     THEN        morph failed
 
+Working with null repositories and refs
+---------------------------------------
+
+It is convenient to not explicitly name the repository and branch of
+a stratum morphology, instead assuming it is the same as the current
+morphology.
+
+These can be checked out like normal system branches.
+
+    SCENARIO    check out an existing system branch with null refs
+    GIVEN       a workspace
+    AND         a git server
+    AND         null refs for local strata
+    WHEN        checking out the master system branch
+    THEN        the system branch master is checked out
+
+Likewise we can also create new system branches from these, and we
+wouldn't need to worry about changing the system branch ref.
+
+
+    SCENARIO    branch off a system branch with null refs
+    GIVEN       a workspace
+    AND         a git server
+    AND         null refs for local strata
+    WHEN        creating system branch foo
+    THEN        the system branch foo is checked out
+
+When we edit a morphology with null refs, they stay null.
+
+    SCENARIO    editing with null refs
+    GIVEN       a workspace
+    AND         a git server
+    AND         null refs for local strata
+
+When creating the branch, the refs remain null.
+
+    WHEN        creating system branch foo
+    THEN        in branch foo, system test-system refs test-stratum in None
+
+After editing the stratum they remain null.
+
+    WHEN    editing stratum test-stratum in system test-system in branch foo
+    THEN    in branch foo, system test-system refs test-stratum in None
+
+Refs to chunks are still altered as usual
+
+    WHEN editing chunk test-chunk in test-stratum in test-system in branch foo
+    THEN in branch foo, system test-system refs test-stratum in None
+    AND  in branch foo, stratum test-stratum refs test-chunk in foo
+    AND  edited chunk test:test-chunk has git branch foo
+
+Petrifying also leaves null refs unmolested
+
+    SCENARIO    morph petrifies null refs
+    GIVEN       a workspace
+    AND         a git server
+    AND         null refs for local strata
+    WHEN        creating system branch foo
+    AND         pushing system branch foo to git server
+    AND         remembering all refs in foo
+    AND         petrifying foo
+    THEN        in branch foo, system test-system refs test-stratum in None
diff --git a/yarns/implementations.yarn b/yarns/implementations.yarn
index cfb744f7..e35e4219 100644
--- a/yarns/implementations.yarn
+++ b/yarns/implementations.yarn
@@ -114,6 +114,18 @@ another to hold a chunk.
     repo-alias = test=file://$DATADIR/gits/%s#file://$DATADIR/gits/%s
     EOF
 
+Morphologies need to support having a null ref, which means look for the
+stratum in the same repository and ref. Testing this requires different
+morphologies.
+
+    IMPLEMENTS GIVEN null refs for local strata
+    nullify_local_refs test:morphs master \
+        "$DATADIR/gits/morphs/test-system.morph" \
+        "$DATADIR/gits/morphs/test-stratum.morph"
+    run_in "$DATADIR/gits/morphs" git add .
+    run_in "$DATADIR/gits/morphs" git commit -m "Use null refs."
+
+
 Implementation sections for system branch operations
 ----------------------------------------------------
 
diff --git a/yarns/morph.shell-lib b/yarns/morph.shell-lib
index 4fb1eb10..41ffbbbd 100644
--- a/yarns/morph.shell-lib
+++ b/yarns/morph.shell-lib
@@ -144,6 +144,27 @@ assert_morphologies_are_petrified()
 }
 
 
+nullify_local_refs()
+{
+    python -c 'import yaml, sys
+repo = sys.argv[1]
+ref = sys.argv[2]
+for filename in sys.argv[3:]:
+    with open(filename, "r") as f:
+        d = yaml.load(f)
+    if "strata" in d:
+        for spec in d["strata"]:
+            if spec["repo"] == repo and spec["ref"] == ref:
+                spec["repo"] = spec["ref"] = None
+    if "build-depends" in d:
+        for spec in d["build-depends"]:
+            if spec["repo"] == repo and spec["ref"] == ref:
+                spec["repo"] = spec["ref"] = None
+    with open(filename, "w") as f:
+        yaml.dump(d, f)
+' "$@"
+}
+
 # Currently, yarn isn't setting $SRCDIR to point at the project source
 # directory. We simulate this here.