diff --git a/tests/kernel-cases/construction/cov-plane-two-edges-meeting-at-a-corner/expected.json b/tests/kernel-cases/construction/cov-plane-two-edges-meeting-at-a-corner/expected.json
new file mode 100644
index 0000000000..3893d49b6d
--- /dev/null
+++ b/tests/kernel-cases/construction/cov-plane-two-edges-meeting-at-a-corner/expected.json
@@ -0,0 +1,22 @@
+{
+ "sources": [],
+ "what": "the plane through two box edges that meet at a corner",
+ "source": "analytic",
+ "method": "box 40 x 30 x 20 with a corner at the origin (x 0..40, y 0..30, z 0..20): the top edges y 0, z 20 (along X) and x 40, z 20 (along Y) meet at (40,0,20): the top, z = 20",
+ "construction": {
+  "E": {
+   "plane": {
+    "through": [
+     1,
+     1,
+     20
+    ],
+    "normal": [
+     0,
+     0,
+     1
+    ]
+   }
+  }
+ }
+}
diff --git a/tests/kernel-cases/construction/cov-plane-two-edges-meeting-at-a-corner/recipe.json b/tests/kernel-cases/construction/cov-plane-two-edges-meeting-at-a-corner/recipe.json
new file mode 100644
index 0000000000..d8df250e43
--- /dev/null
+++ b/tests/kernel-cases/construction/cov-plane-two-edges-meeting-at-a-corner/recipe.json
@@ -0,0 +1,33 @@
+{
+ "commands": [
+  {
+   "command": "solid.box",
+   "params": {
+    "length": 40,
+    "width": 30,
+    "height": 20,
+    "body_name": "Box"
+   }
+  },
+  {
+   "command": "construct.plane.two_edges",
+   "params": {
+    "a": {
+     "edge": [
+      20,
+      0,
+      20
+     ]
+    },
+    "b": {
+     "edge": [
+      40,
+      15,
+      20
+     ]
+    },
+    "name": "E"
+   }
+  }
+ ]
+}
diff --git a/tests/kernel-cases/construction/cov-plane-two-edges-opposite-box-edges/expected.json b/tests/kernel-cases/construction/cov-plane-two-edges-opposite-box-edges/expected.json
new file mode 100644
index 0000000000..1390d905ce
--- /dev/null
+++ b/tests/kernel-cases/construction/cov-plane-two-edges-opposite-box-edges/expected.json
@@ -0,0 +1,22 @@
+{
+ "sources": [],
+ "what": "the plane through a box's bottom-front and top-back edges",
+ "source": "analytic",
+ "method": "box 40 x 30 x 20 with a corner at the origin (x 0..40, y 0..30, z 0..20): both run along X, through (0,0,0) and (0,30,20): normal X x (0,30,20) = (0,-20,30): the plane 3z = 2y, normal (0,-2,3)",
+ "construction": {
+  "E": {
+   "plane": {
+    "through": [
+     5,
+     30,
+     20
+    ],
+    "normal": [
+     0,
+     -2,
+     3
+    ]
+   }
+  }
+ }
+}
diff --git a/tests/kernel-cases/construction/cov-plane-two-edges-opposite-box-edges/recipe.json b/tests/kernel-cases/construction/cov-plane-two-edges-opposite-box-edges/recipe.json
new file mode 100644
index 0000000000..835d05243e
--- /dev/null
+++ b/tests/kernel-cases/construction/cov-plane-two-edges-opposite-box-edges/recipe.json
@@ -0,0 +1,33 @@
+{
+ "commands": [
+  {
+   "command": "solid.box",
+   "params": {
+    "length": 40,
+    "width": 30,
+    "height": 20,
+    "body_name": "Box"
+   }
+  },
+  {
+   "command": "construct.plane.two_edges",
+   "params": {
+    "a": {
+     "edge": [
+      20,
+      0,
+      0
+     ]
+    },
+    "b": {
+     "edge": [
+      20,
+      30,
+      20
+     ]
+    },
+    "name": "E"
+   }
+  }
+ ]
+}
diff --git a/tests/kernel-cases/construction/cov-plane-two-edges-refuses-skew-edges/expected.json b/tests/kernel-cases/construction/cov-plane-two-edges-refuses-skew-edges/expected.json
new file mode 100644
index 0000000000..f061ab2497
--- /dev/null
+++ b/tests/kernel-cases/construction/cov-plane-two-edges-refuses-skew-edges/expected.json
@@ -0,0 +1,8 @@
+{
+ "sources": [],
+ "what": "a plane through two skew box edges",
+ "source": "analytic",
+ "method": "box 40 x 30 x 20 with a corner at the origin (x 0..40, y 0..30, z 0..20): y 0, z 0 along X and x 40, z 20 along Y never meet and are not parallel: no plane holds both: refused",
+ "outcome": "refused",
+ "refusal": "the edges are not in one plane"
+}
diff --git a/tests/kernel-cases/construction/cov-plane-two-edges-refuses-skew-edges/recipe.json b/tests/kernel-cases/construction/cov-plane-two-edges-refuses-skew-edges/recipe.json
new file mode 100644
index 0000000000..ef250537b5
--- /dev/null
+++ b/tests/kernel-cases/construction/cov-plane-two-edges-refuses-skew-edges/recipe.json
@@ -0,0 +1,33 @@
+{
+ "commands": [
+  {
+   "command": "solid.box",
+   "params": {
+    "length": 40,
+    "width": 30,
+    "height": 20,
+    "body_name": "Box"
+   }
+  },
+  {
+   "command": "construct.plane.two_edges",
+   "params": {
+    "a": {
+     "edge": [
+      20,
+      0,
+      0
+     ]
+    },
+    "b": {
+     "edge": [
+      40,
+      15,
+      20
+     ]
+    },
+    "name": "E"
+   }
+  }
+ ]
+}