feat: filling a proposal tally with the median grade

Another brick in the wall for Balancing.

tally.go

@@ -81,3 +81,14 @@ func (proposalTally *ProposalTally) FillWithStaticDefault(upToAmount uint64, def
 
 	return nil
 }
+
+func (proposalTally *ProposalTally) FillWithMedianDefault(upToAmount uint64) (err error) {
+
+	analysis := proposalTally.Analyze()
+	fillErr := proposalTally.FillWithStaticDefault(upToAmount, analysis.MedianGrade)
+	if fillErr != nil {
+		return fillErr
+	}
+
+	return nil
+}

tally_test.go

@@ -107,3 +107,79 @@ func TestProposalTally_FillWithStaticDefaultFailureAmountToLow(t *testing.T) {
 		assert.Equal(t, expectedTally.Tally[i], proposalTally.Tally[i], fmt.Sprintf("Grade #%d", i))
 	}
 }
+
+func TestProposalTally_FillWithStaticDefaultSuccesses(t *testing.T) {
+	type test struct {
+		name           string
+		amountOfJudges uint64
+		defaultGrade   uint8
+		input          ProposalTally
+		expected       ProposalTally
+	}
+	tests := []test{
+		{
+			name:           "Basic usage",
+			amountOfJudges: 30,
+			defaultGrade:   0,
+			input:          ProposalTally{Tally: []uint64{1, 2, 3, 4, 5, 6, 7}},
+			expected:       ProposalTally{Tally: []uint64{3, 2, 3, 4, 5, 6, 7}},
+		},
+		// …
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			proposalTally := tt.input
+			expectedTally := tt.expected
+			err := proposalTally.FillWithStaticDefault(tt.amountOfJudges, tt.defaultGrade)
+			assert.NoError(t, err, "Filling should succeed")
+			for i := 0; i < len(proposalTally.Tally); i++ {
+				assert.Equal(t, expectedTally.Tally[i], proposalTally.Tally[i], fmt.Sprintf("Grade #%d", i))
+			}
+		})
+	}
+}
+
+func TestProposalTally_FillWithMedianDefaultSuccesses(t *testing.T) {
+	type test struct {
+		name           string
+		amountOfJudges uint64
+		input          ProposalTally
+		expected       ProposalTally
+	}
+	tests := []test{
+		{
+			name:           "Basic usage",
+			amountOfJudges: 30,
+			input:          ProposalTally{Tally: []uint64{1, 2, 3, 4, 5, 6, 7}},
+			expected:       ProposalTally{Tally: []uint64{1, 2, 3, 4, 7, 6, 7}},
+		},
+		{
+			name:           "Lots of zeroes",
+			amountOfJudges: 5,
+			input:          ProposalTally{Tally: []uint64{0, 0, 0, 1, 0, 0, 1}},
+			expected:       ProposalTally{Tally: []uint64{0, 0, 0, 4, 0, 0, 1}},
+		},
+		// …
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			proposalTally := tt.input
+			expectedTally := tt.expected
+			err := proposalTally.FillWithMedianDefault(tt.amountOfJudges)
+			assert.NoError(t, err, "Filling should succeed")
+			for i := 0; i < len(proposalTally.Tally); i++ {
+				assert.Equal(t, expectedTally.Tally[i], proposalTally.Tally[i], fmt.Sprintf("Grade #%d", i))
+			}
+		})
+	}
+}
+
+func TestProposalTally_FillWithMedianDefaultFailureAmountToLow(t *testing.T) {
+	proposalTally := ProposalTally{Tally: []uint64{0, 1, 0, 1, 2, 3, 4}}
+	expectedTally := ProposalTally{Tally: []uint64{0, 1, 0, 1, 2, 3, 4}}
+	err := proposalTally.FillWithMedianDefault(5)
+	assert.Error(t, err, "Filling should fail")
+	for i := 0; i < 7; i++ {
+		assert.Equal(t, expectedTally.Tally[i], proposalTally.Tally[i], fmt.Sprintf("Grade #%d", i))
+	}
+}