feat: guess the amount of judges if not explicit

PollTally#GuessAmountOfJudges

judgment/majorityjudgment.go

@@ -36,10 +36,14 @@ func (mj *MajorityJudgment) Deliberate(tally *PollTally) (_ *PollResult, err err
 	}
 
 	amountOfJudges := tally.AmountOfJudges
+	if 0 == amountOfJudges {
+		amountOfJudges = tally.GuessAmountOfJudges()
+	}
 	if amountOfJudges < maximumAmountOfJudgments {
 		return nil, fmt.Errorf("incoherent tally: " +
 			"some proposals hold more judgments than the specified amount of judges ; " +
-			"perhaps you forgot to set PollTally.AmountOfJudges")
+			"perhaps you forgot to set PollTally.AmountOfJudges " +
+			"or to call PollTally.GuessAmountOfJudges()")
 	}
 
 	for proposalIndex, proposalTally := range tally.Proposals {

judgment/majorityjudgment_test.go

@@ -95,6 +95,40 @@ func TestReadmeDemo(t *testing.T) {
 
 }
 
+func TestGuessingAmountOfJudges(t *testing.T) {
+	poll := &PollTally{
+		Proposals: []*ProposalTally{
+			{Tally: []uint64{2, 2, 2, 2, 2}},
+			{Tally: []uint64{2, 1, 1, 1, 5}},
+			{Tally: []uint64{2, 1, 1, 2, 4}},
+			{Tally: []uint64{2, 1, 5, 0, 2}},
+			{Tally: []uint64{2, 2, 2, 2, 2}},
+		},
+	}
+	deliberator := &MajorityJudgment{}
+	result, err := deliberator.Deliberate(poll)
+	assert.NoError(t, err, "Deliberation should succeed")
+	assert.Len(t, result.Proposals, len(poll.Proposals), "There should be as many results as there are tallies.")
+	assert.Equal(t, 4, result.Proposals[0].Rank, "Rank of proposal A")
+	assert.Equal(t, 1, result.Proposals[1].Rank, "Rank of proposal B")
+	assert.Equal(t, 2, result.Proposals[2].Rank, "Rank of proposal C")
+	assert.Equal(t, 3, result.Proposals[3].Rank, "Rank of proposal D")
+	assert.Equal(t, 4, result.Proposals[4].Rank, "Rank of proposal E")
+
+	assert.Equal(t, 1, result.ProposalsSorted[0].Rank, "Rank of sorted proposal A")
+	assert.Equal(t, 2, result.ProposalsSorted[1].Rank, "Rank of sorted proposal 1")
+	assert.Equal(t, 3, result.ProposalsSorted[2].Rank, "Rank of sorted proposal 2")
+	assert.Equal(t, 4, result.ProposalsSorted[3].Rank, "Rank of sorted proposal 3")
+	assert.Equal(t, 4, result.ProposalsSorted[4].Rank, "Rank of sorted proposal 4")
+
+	assert.Equal(t, 1, result.ProposalsSorted[0].Index, "Index of sorted proposal A")
+	assert.Equal(t, 2, result.ProposalsSorted[1].Index, "Index of sorted proposal 1")
+	assert.Equal(t, 3, result.ProposalsSorted[2].Index, "Index of sorted proposal 2")
+	assert.Equal(t, 0, result.ProposalsSorted[3].Index, "Index of sorted proposal 3")
+	assert.Equal(t, 4, result.ProposalsSorted[4].Index, "Index of sorted proposal 4")
+
+}
+
 func TestNoProposals(t *testing.T) {
 	poll := &PollTally{
 		AmountOfJudges: 0,

judgment/tally.go

@@ -1,6 +1,8 @@
 package judgment
 
-import "fmt"
+import (
+	"fmt"
+)
 
 // PollTally describes the amount of judgments received by each proposal on each grade.
 type PollTally struct {
@@ -8,6 +10,18 @@ type PollTally struct {
 	Proposals      []*ProposalTally // Tallies of each proposal.  Its order is preserved in the result.
 }
 
+// GuessAmountOfJudges also mutates the PollTally by filling the AmountOfJudges property
+func (pollTally *PollTally) GuessAmountOfJudges() (_ uint64) {
+	pollTally.AmountOfJudges = 0
+	for _, proposalTally := range pollTally.Proposals {
+		amountOfJudges := proposalTally.CountJudgments()
+		if pollTally.AmountOfJudges < amountOfJudges {
+			pollTally.AmountOfJudges = amountOfJudges
+		}
+	}
+	return pollTally.AmountOfJudges
+}
+
 // BalanceWithStaticDefault mutates the PollTally
 func (pollTally *PollTally) BalanceWithStaticDefault(defaultGrade uint8) (err error) {
 	for _, proposalTally := range pollTally.Proposals {