diff --git a/config/http_config_test.go b/config/http_config_test.go
index 4639ae47..698ea38f 100644
--- a/config/http_config_test.go
+++ b/config/http_config_test.go
@@ -320,10 +320,6 @@ func TestBearerAuthRoundTripper(t *testing.T) {
 }
 
 func TestBearerAuthFileRoundTripper(t *testing.T) {
-	const (
-		newBearerToken = "goodbyeandthankyouforthefish"
-	)
-
 	fakeRoundTripper := NewRoundTripCheckRequest(func(req *http.Request) {
 		bearer := req.Header.Get("Authorization")
 		if bearer != ExpectedBearer {
diff --git a/expfmt/decode_test.go b/expfmt/decode_test.go
index 82c1130c..47c480ef 100644
--- a/expfmt/decode_test.go
+++ b/expfmt/decode_test.go
@@ -258,6 +258,65 @@ func TestProtoDecoder(t *testing.T) {
 				},
 			},
 		},
+		{
+			in: "\u007f\n\x1drequest_duration_microseconds\x12\x15The response latency.\x18\x04\"E:C\b\x85\x15\x11\xcd\xcc\xccL\x8f\xcb:A\x1a\v\b{\x11\x00\x00\x00\x00\x00\x00Y@\x1a\f\b\x9c\x03\x11\x00\x00\x00\x00\x00\x00^@\x1a\f\b\xd0\x04\x11\x00\x00\x00\x00\x00\x00b@\x1a\f\b\xf4\v\x11\x9a\x99\x99\x99\x99\x99e@",
+			expected: model.Vector{
+				&model.Sample{
+					Metric: model.Metric{
+						model.MetricNameLabel: "request_duration_microseconds_count",
+					},
+					Value: 2693,
+					Timestamp:testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						"le": "+Inf",
+						model.MetricNameLabel: "request_duration_microseconds_bucket",
+					},
+					Value: 2693,
+					Timestamp:testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						model.MetricNameLabel: "request_duration_microseconds_sum",
+					},
+					Value: 1756047.3,
+					Timestamp:testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						"le": "172.8",
+						model.MetricNameLabel: "request_duration_microseconds_bucket",
+					},
+					Value: 1524,
+					Timestamp:testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						"le": "144",
+						model.MetricNameLabel: "request_duration_microseconds_bucket",
+					},
+					Value: 592,
+					Timestamp:testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						"le": "120",
+						model.MetricNameLabel: "request_duration_microseconds_bucket",
+					},
+					Value: 412,
+					Timestamp:testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						"le": "100",
+						model.MetricNameLabel: "request_duration_microseconds_bucket",
+					},
+					Value: 123,
+					Timestamp:testTime,
+				},
+			},
+		},
 		{
 			// The metric type is unset in this protobuf, which needs to be handled
 			// correctly by the decoder.
diff --git a/expfmt/encode_test.go b/expfmt/encode_test.go
new file mode 100644
index 00000000..16255e0e
--- /dev/null
+++ b/expfmt/encode_test.go
@@ -0,0 +1,122 @@
+package expfmt
+
+import (
+	"bytes"
+	"github.com/golang/protobuf/proto"
+	dto "github.com/prometheus/client_model/go"
+	"net/http"
+	"testing"
+)
+
+func TestNegotiate(t *testing.T) {
+	acceptValuePrefix := "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily"
+	tests := []struct {
+		name              string
+		acceptHeaderValue string
+		expectedFmt       string
+	}{
+		{
+			name:              "delimited format",
+			acceptHeaderValue: acceptValuePrefix + ";encoding=delimited",
+			expectedFmt:       string(FmtProtoDelim),
+		},
+		{
+			name:              "text format",
+			acceptHeaderValue: acceptValuePrefix + ";encoding=text",
+			expectedFmt:       string(FmtProtoText),
+		},
+		{
+			name:              "compact text format",
+			acceptHeaderValue: acceptValuePrefix + ";encoding=compact-text",
+			expectedFmt:       string(FmtProtoCompact),
+		},
+		{
+			name:              "plain text format",
+			acceptHeaderValue: "text/plain;version=0.0.4",
+			expectedFmt:       string(FmtText),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			h := http.Header{}
+			h.Add(hdrAccept, test.acceptHeaderValue)
+			actualFmt := string(Negotiate(h))
+			if actualFmt != test.expectedFmt {
+				t.Errorf("expected Negotiate to return format %s, but got %s instead", test.expectedFmt, actualFmt)
+			}
+		})
+	}
+}
+
+func TestEncode(t *testing.T) {
+	var buff bytes.Buffer
+	delimEncoder := NewEncoder(&buff, FmtProtoDelim)
+	metric := &dto.MetricFamily{
+		Name: proto.String("foo_metric"),
+		Type: dto.MetricType_UNTYPED.Enum(),
+		Metric: []*dto.Metric{
+			{
+				Untyped: &dto.Untyped{
+					Value: proto.Float64(1.234),
+				},
+			},
+		},
+	}
+
+	err := delimEncoder.Encode(metric)
+	if err != nil {
+		t.Errorf("unexpected error during encode: %s", err.Error())
+	}
+
+	out := buff.Bytes()
+	if len(out) == 0 {
+		t.Errorf("expected the output bytes buffer to be non-empty")
+	}
+
+	buff.Reset()
+
+	compactEncoder := NewEncoder(&buff, FmtProtoCompact)
+	err = compactEncoder.Encode(metric)
+	if err != nil {
+		t.Errorf("unexpected error during encode: %s", err.Error())
+	}
+
+	out = buff.Bytes()
+	if len(out) == 0 {
+		t.Errorf("expected the output bytes buffer to be non-empty")
+	}
+
+	buff.Reset()
+
+	protoTextEncoder := NewEncoder(&buff, FmtProtoText)
+	err = protoTextEncoder.Encode(metric)
+	if err != nil {
+		t.Errorf("unexpected error during encode: %s", err.Error())
+	}
+
+	out = buff.Bytes()
+	if len(out) == 0 {
+		t.Errorf("expected the output bytes buffer to be non-empty")
+	}
+
+	buff.Reset()
+
+	textEncoder := NewEncoder(&buff, FmtText)
+	err = textEncoder.Encode(metric)
+	if err != nil {
+		t.Errorf("unexpected error during encode: %s", err.Error())
+	}
+
+	out = buff.Bytes()
+	if len(out) == 0 {
+		t.Errorf("expected the output bytes buffer to be non-empty")
+	}
+
+	expected := "# TYPE foo_metric untyped\n" +
+		"foo_metric 1.234\n"
+
+	if string(out) != expected {
+		t.Errorf("expected TextEncoder to return %s, but got %s instead", expected, string(out))
+	}
+}
diff --git a/model/metric_test.go b/model/metric_test.go
index 06f9de52..d708b575 100644
--- a/model/metric_test.go
+++ b/model/metric_test.go
@@ -119,6 +119,10 @@ func TestMetricNameIsValid(t *testing.T) {
 			mn:    "colon:in:the:middle",
 			valid: true,
 		},
+		{
+			mn: "",
+			valid: false,
+		},
 	}
 
 	for _, s := range scenarios {