[{:test/label ":db.cardinality/one, insert"
  :test/assertions
  [[:db/add 100 :db/ident :name/Ivan]
   [:db/add 101 :db/ident :name/Petr]]
  :test/expected-transaction
  #{[100 :db/ident :name/Ivan ?tx1 true]
    [101 :db/ident :name/Petr ?tx1 true]
    [?tx1 :db/txInstant ?ms1 ?tx1 true]}
  :test/expected-datoms
  #{[100 :db/ident :name/Ivan]
    [101 :db/ident :name/Petr]}}

 {:test/label "upsert two tempids to same entid"
  :test/assertions
  [[:db/add "t1" :db/ident :name/Ivan]
   [:db/add "t1" :db.schema/attribute 100]
   [:db/add "t2" :db/ident :name/Petr]
   [:db/add "t2" :db.schema/attribute 101]]
  :test/expected-transaction
  #{[100 :db.schema/attribute 100 ?tx2 true]
    [101 :db.schema/attribute 101 ?tx2 true]
    [?tx2 :db/txInstant ?ms2 ?tx2 true]}
  :test/expected-datoms
  #{[100 :db/ident :name/Ivan]
    [101 :db/ident :name/Petr]
    [100 :db.schema/attribute 100]
    [101 :db.schema/attribute 101]}
  :test/expected-tempids
  {"t1" 100
   "t2" 101}}

 {:test/label "upsert with tempid"
  :test/assertions
  [[:db/add "t1" :db/ident :name/Ivan]
   ;; Ref doesn't have to exist (at this time).  Can't reuse due to :db/unique :db.unique/value.
   [:db/add "t1" :db.schema/attribute 102]]
  :test/expected-transaction
  #{[100 :db.schema/attribute 102 ?tx3 true]
    [?tx3 :db/txInstant ?ms3 ?tx3 true]}
  :test/expected-datoms
  #{[100 :db/ident :name/Ivan]
    [101 :db/ident :name/Petr]
    [100 :db.schema/attribute 100]
    [100 :db.schema/attribute 102]
    [101 :db.schema/attribute 101]}
  :test/expected-tempids
  {"t1" 100}}

 ;; TODO: don't hard-code allocated entids.
 {:test/label "single complex upsert allocates new entid"
  :test/assertions
  [[:db/add "t1" :db.schema/attribute "t2"]]
  :test/expected-transaction
  #{[65536 :db.schema/attribute 65537 ?tx4 true]
    [?tx4 :db/txInstant ?ms4 ?tx4 true]}
  :test/expected-tempids
  {"t1" 65536
   "t2" 65537}}

 {:test/label "conflicting upserts fail"
  :test/assertions
  [[:db/add "t1" :db/ident :name/Ivan]
   [:db/add "t1" :db/ident :name/Petr]]
  :test/expected-transaction
  nil
  :test/expected-error-message
  "Conflicting upsert"
  ;; nil
  }

 {:test/label "tempids in :db/retract that do upsert are fine"
  :test/assertions
  [[:db/add "t1" :db/ident :name/Ivan]
   ;; This ref doesn't exist, so the assertion will be ignored.
   [:db/retract "t1" :db.schema/attribute 103]]
  :test/expected-transaction
  #{[?tx6 :db/txInstant ?ms6 ?tx6 true]}
  :test/expected-error-message
  ""
  :test/expected-tempids
  {}}

 {:test/label "tempids in :db/retract that don't upsert fail"
  :test/assertions
  [[:db/retract "t1" :db/ident :name/Anonymous]]
  :test/expected-transaction
  nil
  :test/expected-error-message
  ""}

 ;; The upsert algorithm will first try to resolve "t1", fail, and then allocate both "t1" and "t2".
 {:test/label "multistep, both allocated"
  :test/assertions
  [[:db/add "t1" :db/ident :name/Josef]
   [:db/add "t2" :db.schema/attribute "t1"]]
  :test/expected-transaction
  #{[65538 :db/ident :name/Josef ?tx8 true]
    [65539 :db.schema/attribute 65538 ?tx8 true]
    [?tx8 :db/txInstant ?ms8 ?tx8 true]}
  :test/expected-error-message
  ""
  :test/expected-tempids
  {"t1" 65538
   "t2" 65539}}

 ;; Can't quite test this without more schema elements.
 ;; ;; This time, we can resolve both, but we have to try "t1", succeed, and then resolve "t2".
 ;; {:test/label "multistep, upserted allocated"
 ;;  :test/assertions
 ;;  [[:db/add "t1" :db/ident :name/Josef]
 ;;   [:db/add "t2" :db/ident "t1"]]
 ;;  :test/expected-transaction
 ;;  #{[65538 :db/ident :name/Josef]
 ;;    [65538 :db/ident :name/Karl]
 ;;    [?tx8 :db/txInstant ?ms8 ?tx8 true]}
 ;;  :test/expected-error-message
 ;;  ""
 ;;  :test/expected-tempids
 ;;  {"t1" 65538
 ;;   "t2" 65539}}
 ]