diff --git a/internals/overlord/planstate/manager_test.go b/internals/overlord/planstate/manager_test.go
index ef28f43d..3da0debf 100644
--- a/internals/overlord/planstate/manager_test.go
+++ b/internals/overlord/planstate/manager_test.go
@@ -45,52 +45,6 @@ var loadLayers = []string{`
 			summary: Svc1
 			override: replace
 			command: echo svc1
-`, `
-	summary: Layer 2
-	description: Layer 2 desc.
-	services:
-		svc2:
-			summary: Svc2
-			override: replace
-			command: echo svc2
-`}
-
-func (ps *planSuite) TestLoadLayers(c *C) {
-	var err error
-	ps.planMgr, err = planstate.NewManager(ps.layersDir)
-	c.Assert(err, IsNil)
-	// Write layers
-	for _, l := range loadLayers {
-		ps.writeLayer(c, string(reindent(l)))
-	}
-	// Load the plan from the <pebble-dir>/layers directory
-	err = ps.planMgr.Load()
-	c.Assert(err, IsNil)
-	plan := ps.planMgr.Plan()
-	out, err := yaml.Marshal(plan)
-	c.Assert(err, IsNil)
-	c.Assert(len(plan.Layers), Equals, 2)
-	c.Assert(string(out), Equals, `
-services:
-    svc1:
-        summary: Svc1
-        override: replace
-        command: echo svc1
-    svc2:
-        summary: Svc2
-        override: replace
-        command: echo svc2
-`[1:])
-}
-
-var extLoadLayers = []string{`
-	summary: Layer 1
-	description: Layer 1 desc.
-	services:
-		svc1:
-			summary: Svc1
-			override: replace
-			command: echo svc1
 	test-field:
 		test1:
 			override: merge
@@ -109,15 +63,14 @@ var extLoadLayers = []string{`
 			b: something else
 `}
 
-func (ps *planSuite) TestExtLoadLayers(c *C) {
+func (ps *planSuite) TestLoadLayers(c *C) {
 	plan.RegisterExtension(testField, testExtension{})
 	defer plan.UnregisterExtension(testField)
-
 	var err error
 	ps.planMgr, err = planstate.NewManager(ps.layersDir)
 	c.Assert(err, IsNil)
 	// Write layers
-	for _, l := range extLoadLayers {
+	for _, l := range loadLayers {
 		ps.writeLayer(c, string(reindent(l)))
 	}
 	// Load the plan from the <pebble-dir>/layers directory
@@ -146,89 +99,8 @@ test-field:
 }
 
 func (ps *planSuite) TestAppendLayers(c *C) {
-	var err error
-	ps.planMgr, err = planstate.NewManager(ps.layersDir)
-	c.Assert(err, IsNil)
-
-	// Append a layer when there are no layers.
-	layer := ps.parseLayer(c, 0, "label1", `
-services:
-    svc1:
-        override: replace
-        command: /bin/sh
-`)
-	err = ps.planMgr.AppendLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 1)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/sh
-`[1:])
-	ps.planLayersHasLen(c, 1)
-
-	// Try to append a layer when that label already exists.
-	layer = ps.parseLayer(c, 0, "label1", `
-services:
-    svc1:
-        override: foobar
-        command: /bin/bar
-`)
-	err = ps.planMgr.AppendLayer(layer)
-	c.Assert(err.(*planstate.LabelExists).Label, Equals, "label1")
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/sh
-`[1:])
-	ps.planLayersHasLen(c, 1)
-
-	// Append another layer on top.
-	layer = ps.parseLayer(c, 0, "label2", `
-services:
-    svc1:
-        override: replace
-        command: /bin/bash
-`)
-	err = ps.planMgr.AppendLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 2)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/bash
-`[1:])
-	ps.planLayersHasLen(c, 2)
-
-	// Append a layer with a different service.
-	layer = ps.parseLayer(c, 0, "label3", `
-services:
-    svc2:
-        override: replace
-        command: /bin/foo
-`)
-	err = ps.planMgr.AppendLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 3)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/bash
-    svc2:
-        override: replace
-        command: /bin/foo
-`[1:])
-	ps.planLayersHasLen(c, 3)
-}
-
-func (ps *planSuite) TestExtAppendLayers(c *C) {
 	plan.RegisterExtension(testField, testExtension{})
 	defer plan.UnregisterExtension(testField)
-
 	var err error
 	ps.planMgr, err = planstate.NewManager(ps.layersDir)
 	c.Assert(err, IsNil)
@@ -344,131 +216,8 @@ test-field:
 }
 
 func (ps *planSuite) TestCombineLayers(c *C) {
-	var err error
-	ps.planMgr, err = planstate.NewManager(ps.layersDir)
-	c.Assert(err, IsNil)
-
-	// "Combine" layer with no layers should just append.
-	layer := ps.parseLayer(c, 0, "label1", `
-services:
-    svc1:
-        override: replace
-        command: /bin/sh
-`)
-	err = ps.planMgr.CombineLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 1)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/sh
-`[1:])
-	ps.planLayersHasLen(c, 1)
-
-	// Combine layer with different label should just append.
-	layer = ps.parseLayer(c, 0, "label2", `
-services:
-    svc2:
-        override: replace
-        command: /bin/foo
-`)
-	err = ps.planMgr.CombineLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 2)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/sh
-    svc2:
-        override: replace
-        command: /bin/foo
-`[1:])
-	ps.planLayersHasLen(c, 2)
-
-	// Combine layer with first layer.
-	layer = ps.parseLayer(c, 0, "label1", `
-services:
-    svc1:
-        override: replace
-        command: /bin/bash
-`)
-	err = ps.planMgr.CombineLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 1)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/bash
-    svc2:
-        override: replace
-        command: /bin/foo
-`[1:])
-	ps.planLayersHasLen(c, 2)
-
-	// Combine layer with second layer.
-	layer = ps.parseLayer(c, 0, "label2", `
-services:
-    svc2:
-        override: replace
-        command: /bin/bar
-`)
-	err = ps.planMgr.CombineLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 2)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/bash
-    svc2:
-        override: replace
-        command: /bin/bar
-`[1:])
-	ps.planLayersHasLen(c, 2)
-
-	// One last append for good measure.
-	layer = ps.parseLayer(c, 0, "label3", `
-services:
-    svc1:
-        override: replace
-        command: /bin/a
-    svc2:
-        override: replace
-        command: /bin/b
-`)
-	err = ps.planMgr.CombineLayer(layer)
-	c.Assert(err, IsNil)
-	c.Assert(layer.Order, Equals, 3)
-	c.Assert(ps.planYAML(c), Equals, `
-services:
-    svc1:
-        override: replace
-        command: /bin/a
-    svc2:
-        override: replace
-        command: /bin/b
-`[1:])
-	ps.planLayersHasLen(c, 3)
-
-	// Make sure that layer validation is happening.
-	layer, err = plan.ParseLayer(0, "label4", []byte(`
-checks:
-    bad-check:
-        override: replace
-        level: invalid
-        tcp:
-            port: 8080
-`))
-	c.Check(err, ErrorMatches, `(?s).*plan check.*must be "alive" or "ready".*`)
-}
-
-func (ps *planSuite) TestExtCombineLayers(c *C) {
 	plan.RegisterExtension(testField, testExtension{})
 	defer plan.UnregisterExtension(testField)
-
 	var err error
 	ps.planMgr, err = planstate.NewManager(ps.layersDir)
 	c.Assert(err, IsNil)