simplify test code

testing/unit/assertions.go

@@ -4,6 +4,8 @@ import (
 	"testing"
 )
 
+// Assertion is an assertion library inspired by Truth.
+// See http://google.github.io/truth/
 type Assertion struct {
 	t *testing.T
 }
@@ -29,3 +31,11 @@ func (a *Assertion) Byte(value byte) *ByteSubject {
 func (a *Assertion) Bytes(value []byte) *BytesSubject {
 	return NewBytesSubject(NewSubject(a), value)
 }
+
+func (a *Assertion) String(value string) *StringSubject {
+  return NewStringSubject(NewSubject(a), value)
+}
+
+func (a *Assertion) Error(value error) *ErrorSubject {
+  return NewErrorSubject(NewSubject(a), value)
+}

testing/unit/errorsubject.go

@@ -0,0 +1,42 @@
+package unit
+
+import (
+  "fmt"
+)
+
+type ErrorSubject struct {
+	*Subject
+	value error
+}
+
+func NewErrorSubject(base *Subject, value error) *ErrorSubject {
+	subject := new(StringSubject)
+	subject.Subject = base
+	subject.value = value
+	return subject
+}
+
+func (subject *ErrorSubject) Named(name string) *ErrorSubject {
+	subject.Subject.Named(name)
+	return subject
+}
+
+func (subject *ErrorSubject) Fail(verb string, other error) {
+	subject.FailWithMessage("Not true that " + subject.DisplayString() + " " + verb + " <" + other.Error() + ">.")
+}
+
+func (subject *ErrorSubject) DisplayString() string {
+	return subject.Subject.DisplayString(subject.value.Error())
+}
+
+func (subject *ErrorSubject) Equals(expectation error) {
+	if subject.value != expectation {
+		subject.Fail("is equal to", expectation)
+	}
+}
+
+func (subject *ErrorSubject) IsNil() {
+  if subject.value != nil {
+    subject.FailWithMethod("Not true that " + subject.DisplayString() + " is nil.")
+  }
+}

testing/unit/stringsubject.go

@@ -0,0 +1,32 @@
+package unit
+
+type StringSubject struct {
+	*Subject
+	value string
+}
+
+func NewStringSubject(base *Subject, value string) *StringSubject {
+	subject := new(StringSubject)
+	subject.Subject = base
+	subject.value = value
+	return subject
+}
+
+func (subject *StringSubject) Named(name string) *StringSubject {
+	subject.Subject.Named(name)
+	return subject
+}
+
+func (subject *StringSubject) Fail(verb string, other string) {
+	subject.FailWithMessage("Not true that " + subject.DisplayString() + " " + verb + " <" + other + ">.")
+}
+
+func (subject *StringSubject) DisplayString() string {
+	return subject.Subject.DisplayString(subject.value)
+}
+
+func (subject *StringSubject) Equals(expectation string) {
+	if subject.value != expectation {
+		subject.Fail("is equal to", expectation)
+	}
+}