Add test for Upsert block

[mangalaman93]

Should merge it after the PR dgraph-io/dgraph#3412 is merged.

This change is 

[manishrjain]

Reviewed 1 of 1 files at r1.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @gitlw, @mangalaman93, @martinmr, and @pawanrawal)

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examples_test.go, line 1064 at r1 (raw file):

	defer toCancel()
	err := dg.Alter(ctx, &api.Operation{
		DropAll: true,

Add a warning so people don't accidentally copy paste this. See below.

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examples_test.go, line 1100 at r1 (raw file):

	`
	m2 := `uid(v) <email> "user@dgraph.io" .`
	mu.SetNquads = []byte(m2)

Might make sense to also do a deletion of uid(v) <email> "user@dgraph0.io" .

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examples_test.go, line 1131 at r1 (raw file):

	ctx := context.Background()
	if err := dg.Alter(ctx, &api.Operation{DropAll: true}); err != nil {

Add warning here to remove this line if you're copy pasting this.

[mangalaman93]

Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @gitlw, @manishrjain, @martinmr, and @pawanrawal)

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examples_test.go, line 1064 at r1 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

Add a warning so people don't accidentally copy paste this. See below.

Done.

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examples_test.go, line 1100 at r1 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

Might make sense to also do a deletion of uid(v) <email> "user@dgraph0.io" .

We are overriding the email here. That'd not be required.

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examples_test.go, line 1131 at r1 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

Add warning here to remove this line if you're copy pasting this.

Done.

[gitlw]

Reviewable status: 0 of 1 files reviewed, 4 unresolved discussions (waiting on @mangalaman93, @manishrjain, @martinmr, and @pawanrawal)

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examples_test.go, line 1167 at r2 (raw file):

		log.Fatal(err)
	}

Add a query and print the output here to verify that the name is Wrong.

[gitlw]

except for the minor comment below

Reviewable status: 0 of 1 files reviewed, 4 unresolved discussions (waiting on @mangalaman93, @manishrjain, @martinmr, and @pawanrawal)

[martinmr]

Reviewed 1 of 1 files at r2.
Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @mangalaman93, @manishrjain, and @pawanrawal)

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examples_test.go, line 1218 at r2 (raw file):

	fmt.Println(string(resp.Json))
	// Output: {"Me":[{"age":35,"name":"user","email":"user@dgraph.io"}]}
	// {"Me":[]}

what's this second commented out line supposed to mean?

[mangalaman93]

Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @mangalaman93, @manishrjain, @martinmr, and @pawanrawal)

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examples_test.go, line 1218 at r2 (raw file):

Previously, martinmr (Martin Martinez Rivera) wrote…

what's this second commented out line supposed to mean?

That's the part of the output as well.