command/format: Render empty JSON object as {}

command/format/diff.go

@@ -438,11 +438,15 @@ func (p *blockBodyDiffPrinter) writeValue(val cty.Value, action plans.Action, in
 					jv, err := ctyjson.Unmarshal(src, ty)
 					if err == nil {
 						p.buf.WriteString("jsonencode(")
-						p.buf.WriteByte('\n')
-						p.buf.WriteString(strings.Repeat(" ", indent+4))
-						p.writeValue(jv, action, indent+4)
-						p.buf.WriteByte('\n')
-						p.buf.WriteString(strings.Repeat(" ", indent))
+						if jv.LengthInt() == 0 {
+							p.writeValue(jv, action, 0)
+						} else {
+							p.buf.WriteByte('\n')
+							p.buf.WriteString(strings.Repeat(" ", indent+4))
+							p.writeValue(jv, action, indent+4)
+							p.buf.WriteByte('\n')
+							p.buf.WriteString(strings.Repeat(" ", indent))
+						}
 						p.buf.WriteByte(')')
 						break // don't *also* do the normal behavior below
 					}
@@ -505,7 +509,7 @@ func (p *blockBodyDiffPrinter) writeValue(val cty.Value, action plans.Action, in
 		}
 		p.buf.WriteString("}")
 	case ty.IsObjectType():
-		p.buf.WriteString("{\n")
+		p.buf.WriteString("{")
 
 		atys := ty.AttributeTypes()
 		attrNames := make([]string, 0, len(atys))
@@ -520,16 +524,20 @@ func (p *blockBodyDiffPrinter) writeValue(val cty.Value, action plans.Action, in
 
 		for _, attrName := range attrNames {
 			val := val.GetAttr(attrName)
+
+			p.buf.WriteString("\n")
 			p.buf.WriteString(strings.Repeat(" ", indent+2))
 			p.writeActionSymbol(action)
 			p.buf.WriteString(attrName)
 			p.buf.WriteString(strings.Repeat(" ", nameLen-len(attrName)))
 			p.buf.WriteString(" = ")
 			p.writeValue(val, action, indent+4)
-			p.buf.WriteString("\n")
 		}
 
-		p.buf.WriteString(strings.Repeat(" ", indent))
+		if len(attrNames) > 0 {
+			p.buf.WriteString("\n")
+			p.buf.WriteString(strings.Repeat(" ", indent))
+		}
 		p.buf.WriteString("}")
 	}
 }

command/format/diff_test.go

@@ -414,6 +414,28 @@ func TestResourceChange_JSON(t *testing.T) {
             }
         )
     }
+`,
+		},
+		"creation (empty)": {
+			Action: plans.Create,
+			Mode:   addrs.ManagedResourceMode,
+			Before: cty.NullVal(cty.EmptyObject),
+			After: cty.ObjectVal(map[string]cty.Value{
+				"id":         cty.UnknownVal(cty.String),
+				"json_field": cty.StringVal(`{}`),
+			}),
+			Schema: &configschema.Block{
+				Attributes: map[string]*configschema.Attribute{
+					"id":         {Type: cty.String, Optional: true, Computed: true},
+					"json_field": {Type: cty.String, Optional: true},
+				},
+			},
+			RequiredReplace: cty.NewPathSet(),
+			ExpectedOutput: `  # test_instance.example will be created
+  + resource "test_instance" "example" {
+      + id         = (known after apply)
+      + json_field = jsonencode({})
+    }
 `,
 		},
 	}