all: make tests pass when -count is greater than 1

Tests run repeatedly do not reinitialise state, meaning that a second run
of the tests will have leftover state from the previous run. This ensures
that repeated runs are identical with the exception of map iteration order.

graph/graph_test.go

@@ -17,7 +17,8 @@ type graphBuilder interface {
 	graph.Builder
 }
 
-var copyTests = []struct {
+func TestCopy(t *testing.T) {
+	copyTests := []struct {
 		desc string
 
 		src graph.Graph
@@ -123,7 +124,6 @@ var copyTests = []struct {
 		},
 	}
 
-func TestCopy(t *testing.T) {
 	for _, test := range copyTests {
 		graph.Copy(test.dst, test.src)
 		want := test.want
@@ -141,7 +141,8 @@ type graphWeightedBuilder interface {
 	graph.WeightedBuilder
 }
 
-var copyWeightedTests = []struct {
+func TestCopyWeighted(t *testing.T) {
+	copyWeightedTests := []struct {
 		desc string
 
 		src graph.Weighted
@@ -247,7 +248,6 @@ var copyWeightedTests = []struct {
 		},
 	}
 
-func TestCopyWeighted(t *testing.T) {
 	for _, test := range copyWeightedTests {
 		graph.CopyWeighted(test.dst, test.src)
 		want := test.want

graph/layout/eades_test.go

@@ -19,7 +19,8 @@ import (
 	. "gonum.org/v1/gonum/graph/layout"
 )
 
-var eadesR2Tests = []struct {
+func TestEadesR2(t *testing.T) {
+	eadesR2Tests := []struct {
 		name      string
 		g         graph.Graph
 		param     EadesR2
@@ -196,7 +197,6 @@ var eadesR2Tests = []struct {
 		},
 	}
 
-func TestEadesR2(t *testing.T) {
 	for _, test := range eadesR2Tests {
 		eades := test.param
 		o := NewOptimizerR2(test.g, eades.Update)

graph/layout/isomap_test.go

@@ -28,7 +28,8 @@ var (
 	arch string
 )
 
-var isomapR2Tests = []struct {
+func TestIsomapR2(t *testing.T) {
+	isomapR2Tests := []struct {
 		name string
 		g    graph.Graph
 	}{
@@ -159,7 +160,6 @@ var isomapR2Tests = []struct {
 		},
 	}
 
-func TestIsomapR2(t *testing.T) {
 	for _, test := range isomapR2Tests {
 		o := NewOptimizerR2(test.g, IsomapR2{}.Update)
 		var n int

graph/nodes_edges_test.go

@@ -21,7 +21,12 @@ import (
 // weightedlines
 // empty
 
-var nodesOfTests = []struct {
+type basicNodes struct {
+	graph.Nodes
+}
+
+func TestNodesOf(t *testing.T) {
+	nodesOfTests := []struct {
 		name  string
 		nodes graph.Nodes
 		want  []graph.Node
@@ -58,11 +63,6 @@ var nodesOfTests = []struct {
 		},
 	}
 
-type basicNodes struct {
-	graph.Nodes
-}
-
-func TestNodesOf(t *testing.T) {
 	for _, test := range nodesOfTests {
 		got := graph.NodesOf(test.nodes)
 		if !reflect.DeepEqual(got, test.want) {
@@ -71,7 +71,12 @@ func TestNodesOf(t *testing.T) {
 	}
 }
 
-var edgesOfTests = []struct {
+type basicEdges struct {
+	graph.Edges
+}
+
+func TestEdgesOf(t *testing.T) {
+	edgesOfTests := []struct {
 		name  string
 		edges graph.Edges
 		want  []graph.Edge
@@ -119,11 +124,6 @@ var edgesOfTests = []struct {
 		},
 	}
 
-type basicEdges struct {
-	graph.Edges
-}
-
-func TestEdgesOf(t *testing.T) {
 	for _, test := range edgesOfTests {
 		got := graph.EdgesOf(test.edges)
 		if !reflect.DeepEqual(got, test.want) {
@@ -132,7 +132,12 @@ func TestEdgesOf(t *testing.T) {
 	}
 }
 
-var weightedEdgesOfTests = []struct {
+type basicWeightedEdges struct {
+	graph.WeightedEdges
+}
+
+func TestWeightedEdgesOf(t *testing.T) {
+	weightedEdgesOfTests := []struct {
 		name  string
 		edges graph.WeightedEdges
 		want  []graph.WeightedEdge
@@ -180,11 +185,6 @@ var weightedEdgesOfTests = []struct {
 		},
 	}
 
-type basicWeightedEdges struct {
-	graph.WeightedEdges
-}
-
-func TestWeightedEdgesOf(t *testing.T) {
 	for _, test := range weightedEdgesOfTests {
 		got := graph.WeightedEdgesOf(test.edges)
 		if !reflect.DeepEqual(got, test.want) {
@@ -193,7 +193,12 @@ func TestWeightedEdgesOf(t *testing.T) {
 	}
 }
 
-var linesOfTests = []struct {
+type basicLines struct {
+	graph.Lines
+}
+
+func TestLinesOf(t *testing.T) {
+	linesOfTests := []struct {
 		name  string
 		lines graph.Lines
 		want  []graph.Line
@@ -241,11 +246,6 @@ var linesOfTests = []struct {
 		},
 	}
 
-type basicLines struct {
-	graph.Lines
-}
-
-func TestLinesOf(t *testing.T) {
 	for _, test := range linesOfTests {
 		got := graph.LinesOf(test.lines)
 		if !reflect.DeepEqual(got, test.want) {
@@ -254,7 +254,12 @@ func TestLinesOf(t *testing.T) {
 	}
 }
 
-var weightedLinesOfTests = []struct {
+type basicWeightedLines struct {
+	graph.WeightedLines
+}
+
+func TestWeightedLinesOf(t *testing.T) {
+	weightedLinesOfTests := []struct {
 		name  string
 		lines graph.WeightedLines
 		want  []graph.WeightedLine
@@ -302,11 +307,6 @@ var weightedLinesOfTests = []struct {
 		},
 	}
 
-type basicWeightedLines struct {
-	graph.WeightedLines
-}
-
-func TestWeightedLinesOf(t *testing.T) {
 	for _, test := range weightedLinesOfTests {
 		got := graph.WeightedLinesOf(test.lines)
 		if !reflect.DeepEqual(got, test.want) {

stat/samplemv/sample_test.go

@@ -163,11 +163,12 @@ func TestMetropolisHastings(t *testing.T) {
 	compareNormal(t, target, batch, nil, 5e-1, 5e-1)
 }
 
-// randomNormal constructs a random Normal distribution.
+// randomNormal constructs a random Normal distribution using the provided
+// random source.
 func randomNormal(dim int, src *rand.Rand) (*distmv.Normal, bool) {
 	data := make([]float64, dim*dim)
 	for i := range data {
-		data[i] = rand.Float64()
+		data[i] = src.Float64()
 	}
 	a := mat.NewDense(dim, dim, data)
 	var sigma mat.SymDense
@@ -180,6 +181,8 @@ func randomNormal(dim int, src *rand.Rand) (*distmv.Normal, bool) {
 }
 
 func compareNormal(t *testing.T, want *distmv.Normal, batch *mat.Dense, weights []float64, meanTol, covTol float64) {
+	t.Helper()
+
 	dim := want.Dim()
 	mu := want.Mean(nil)
 	var sigma mat.SymDense
@@ -224,10 +227,11 @@ func TestMetropolisHastingser(t *testing.T) {
 		{3, 103, 11, 51},
 		{3, 103, 51, 11},
 	} {
+		src := rand.New(rand.NewSource(1))
 		dim := test.dim
 
 		initial := make([]float64, dim)
-		target, ok := randomNormal(dim, nil)
+		target, ok := randomNormal(dim, src)
 		if !ok {
 			t.Fatal("bad test, sigma not pos def")
 		}
@@ -239,7 +243,7 @@ func TestMetropolisHastingser(t *testing.T) {
 
 		// Test the Metropolis Hastingser by generating all the samples, then generating
 		// the same samples with a burnin and rate.
-		src := rand.New(rand.NewSource(1))
+		src = rand.New(rand.NewSource(1))
 		proposal, ok := NewProposalNormal(sigmaImp, src)
 		if !ok {
 			t.Fatal("bad test, sigma not pos def")

unit/unit_test.go

@@ -185,7 +185,8 @@ func TestDimensionEquality(t *testing.T) {
 	}
 }
 
-var operationTests = []struct {
+func TestOperations(t *testing.T) {
+	operationTests := []struct {
 		recvOp func(Uniter) *Unit
 		param  Uniter
 		want   Uniter
@@ -197,8 +198,6 @@ var operationTests = []struct {
 		{Dimless(1).Unit().Div, Length(2), New(0.5, Dimensions{LengthDim: -1})},
 		{Length(1).Unit().Div, Dimless(2), Length(0.5)},
 	}
-
-func TestOperations(t *testing.T) {
 	t.Parallel()
 	for i, test := range operationTests {
 		var got Uniter