prior may be unknown when planning data sources

While the proposed plan value for managed resource is only a suggestion,
deferred data sources must be completely planed by core, hence set
appropriate unknown values. We do this by using a prior unknown, which
must be taken into account by all nested types.

internal/plans/objchange/objchange.go

@@ -229,7 +229,6 @@ func proposedNewNestingList(schema nestedSchema, prior, config cty.Value) cty.Va
 
 func proposedNewNestingMap(schema nestedSchema, prior, config cty.Value) cty.Value {
 	newV := config
-
 	newVals := map[string]cty.Value{}
 
 	if config.IsNull() || !config.IsKnown() || config.LengthInt() == 0 {
@@ -239,7 +238,7 @@ func proposedNewNestingMap(schema nestedSchema, prior, config cty.Value) cty.Val
 	}
 	cfgMap := config.AsValueMap()
 
-	// prior may be null or empty
+	// prior may be null, empty or unknown
 	priorMap := map[string]cty.Value{}
 	if !prior.IsNull() && prior.IsKnown() && prior.LengthInt() > 0 {
 		priorMap = prior.AsValueMap()
@@ -248,10 +247,13 @@ func proposedNewNestingMap(schema nestedSchema, prior, config cty.Value) cty.Val
 	for name, configEV := range cfgMap {
 		priorEV, inPrior := priorMap[name]
 		if !inPrior {
-			// If there is no corresponding prior element then
-			// we just take the config value as-is.
-			newVals[name] = configEV
-			continue
+			// if the prior cty.Map value was unknown the map won't have any
+			// keys, so generate an unknown value.
+			if !prior.IsKnown() {
+				priorEV = cty.UnknownVal(configEV.Type())
+			} else {
+				priorEV = cty.NullVal(configEV.Type())
+			}
 		}
 
 		newVals[name] = proposedNewBlockOrObject(schema, priorEV, configEV)
@@ -339,9 +341,7 @@ func proposedNewAttributes(attrs map[string]*configschema.Attribute, prior, conf
 		} else {
 			priorV = prior.GetAttr(name)
 		}
-
 		configV := config.GetAttr(name)
-
 		var newV cty.Value
 		switch {
 		// required isn't considered when constructing the plan, so attributes

internal/plans/objchange/objchange_test.go

@@ -954,7 +954,7 @@ func TestProposedNew(t *testing.T) {
 					}),
 					"c": cty.ObjectVal(map[string]cty.Value{
 						"bar": cty.StringVal("bosh"),
-						"baz": cty.NullVal(cty.List(cty.String)),
+						"baz": cty.NullVal(cty.DynamicPseudoType),
 					}),
 				}),
 				"bloop": cty.ObjectVal(map[string]cty.Value{
@@ -1920,7 +1920,7 @@ func TestProposedNew(t *testing.T) {
 							Attributes: map[string]*configschema.Attribute{
 								"map": {
 									NestedType: &configschema.Object{
-										Nesting: configschema.NestingList,
+										Nesting: configschema.NestingMap,
 										Attributes: map[string]*configschema.Attribute{
 											"foo": {
 												Type: cty.String,
@@ -1942,7 +1942,7 @@ func TestProposedNew(t *testing.T) {
 					})),
 				}),
 				"map": cty.Map(cty.Object(map[string]cty.Type{
-					"list": cty.List(cty.Object(map[string]cty.Type{
+					"map": cty.List(cty.Object(map[string]cty.Type{
 						"foo": cty.String,
 					})),
 				})),
@@ -1960,11 +1960,11 @@ func TestProposedNew(t *testing.T) {
 				}),
 				"map": cty.MapVal(map[string]cty.Value{
 					"one": cty.ObjectVal(map[string]cty.Value{
-						"list": cty.ListVal([]cty.Value{
-							cty.ObjectVal(map[string]cty.Value{
+						"map": cty.MapVal(map[string]cty.Value{
+							"one": cty.ObjectVal(map[string]cty.Value{
 								"foo": cty.StringVal("a"),
 							}),
-							cty.ObjectVal(map[string]cty.Value{
+							"two": cty.ObjectVal(map[string]cty.Value{
 								"foo": cty.StringVal("b"),
 							}),
 						}),
@@ -1984,11 +1984,11 @@ func TestProposedNew(t *testing.T) {
 				}),
 				"map": cty.MapVal(map[string]cty.Value{
 					"one": cty.ObjectVal(map[string]cty.Value{
-						"list": cty.ListVal([]cty.Value{
-							cty.ObjectVal(map[string]cty.Value{
+						"map": cty.MapVal(map[string]cty.Value{
+							"one": cty.ObjectVal(map[string]cty.Value{
 								"foo": cty.StringVal("a"),
 							}),
-							cty.ObjectVal(map[string]cty.Value{
+							"two": cty.ObjectVal(map[string]cty.Value{
 								"foo": cty.StringVal("b"),
 							}),
 						}),