Add alias for `t` receiver type name

[alvinmatias69]

Create alias tr for receiver with name t to avoid conflict with the test parameters (t *testing.T). Also, add unit test for method with t receiver type name and fixes conflict unit tests accordingly.

func TestTestReceiver_FooMethod(t *testing.T) {
    tests := []struct {
        name    string
-       t       *TestReceiver
+       tr      *TestReceiver
        wantErr bool
    }{
        // TODO: Add test cases.
    }
    for _, tt := range tests {
-       t := &TestReceiver{}
-       if err := t.FooMethod(); (err != nil) != tt.wantErr {
+       tr := &TestReceiver{}
+       if err := tr.FooMethod(); (err != nil) != tt.wantErr {
    ...

fix #100

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[coveralls]

Coverage increased (+0.02%) to 96.399% when pulling d66e2bb6a88d84465e74ef0a4f257634005b5e35 on alvinmatias69:fix_t_receiver into 88d586d842701ac013a269d0b2445b68f64850a0 on cweill:develop.

[alvinmatias69]

@googlebot I signed it!

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