Add a test for partial builds

Change-Id: Ibc95fe1d78c8d68dd20a4d2187f93f363369dfec

2 files changed, 17 insertions, 0 deletions

diff --git a/yarns/building.yarn b/yarns/building.yarn
index b5e46b73..8a98e5d9 100644
--- a/yarns/building.yarn
+++ b/yarns/building.yarn
@@ -112,3 +112,14 @@ Empty strata don't build
     AND the user attempts to build the system systems/empty-stratum-system.morph in branch empty-stratum
     THEN morph failed
     FINALLY the git server is shut down
+
+Partial building
+----------------
+
+    SCENARIO partial building
+    GIVEN a workspace
+    AND a git server
+    WHEN the user checks out the system branch called master
+    AND the user attempts to build build-essential from the system systems/test-system.morph in branch master
+    THEN morph succeeded
+    FINALLY the git server is shut down
diff --git a/yarns/implementations.yarn b/yarns/implementations.yarn
index 2bbb1f5c..faae44a8 100644
--- a/yarns/implementations.yarn
+++ b/yarns/implementations.yarn
@@ -737,6 +737,12 @@ Implementation sections for building
     if [ "$MATCH_1" != "attempts to " ]; then run_morph "$@"
     else attempt_morph "$@"; fi
 
+    IMPLEMENTS WHEN the user (attempts to )?((dist)?build)s? (\S+) from the system (\S+) in branch (\S+)
+    cd "$DATADIR/workspace/$MATCH_6/test/morphs"
+    set "$MATCH_2" "$MATCH_5" "$MATCH_4"
+    if [ "$MATCH_1" != "attempts to " ]; then run_morph "$@"
+    else attempt_morph "$@"; fi
+
 Implementation sections for cross-bootstraping
 ==============================================