Tools · Web testing tools · 06 / 23
Comparer: what changed between two lab responses
Comparer lines up two responses you already collected and shows the words that differ. On Harbor Ledger the useful pair is Avery’s two own invoices, so the diff teaches the tool on data the account was allowed to read.
Pick two responses of the same kind
Comparer is a diff for messages you already have. In the lab, load invoice 1042 and invoice 1048 while signed in as Avery. Both are Avery’s seed data: April retainer is open, March hosting is paid. Right-click each history response and send it to Comparer. Compare the responses, and choose words rather than bytes.
The screen then shows the two bodies with the changed words marked. You are not asking the tool to judge the app. You are asking it to point at the words so you do not miss a field that scrolled off the pane. The same gesture works later for “the response before I clicked save” and “the response after,” which is a bug-confirmation habit.
Read the highlight as a list of fields
On this pair the highlighted JSON fields are the id, the title, and the invoice status. The owner field is present on both sides and is not highlighted, because both values are avery@ledger.lab. Write the owner down as the field that stayed put. A diff that only mentions what changed leaves out the fact that made the pair legitimate to compare.
Headers will highlight too. Date changes every response. Content-Length may change because the titles differ in size. Those are real differences and they are the wrong story. Your note can say “ignored Date and Content-Length” in one clause, then list the JSON fields. Anyone reading the note can repeat the comparison and agree.
Left response: GET /api/invoices/1042 Right response: GET /api/invoices/1048 Comparison: words Same field: owner = avery@ledger.lab Changed: id, title, status Ignored: Date, Content-Length
When bytes are the better view
Switch to bytes when you expected two responses to be identical and the word view looks quiet but the lengths differ. A single changed character inside a token, or a reordered key, is easier to see when the tool is not grouping letters into words. For Harbor Ledger’s pretty JSON, words are enough.
If you compare a response to itself, the word view should be quiet except for headers you already called noise. That is a sanity check that you sent the same item twice, not two different items. Repeater’s send list is a convenient source for that pair: send 1 and send 2 of the same tab.
Worked case: April retainer against March hosting
Build the pair as above. Write five lines: the two paths, the comparison mode, the fields that match, the fields that differ with both values, and the headers you ignored. If owner is highlighted, stop and quote both owner strings from these two responses. That would mean the account you signed in as received a row that names someone else, and the quote is the whole confirmation you need.
Close Comparer when the note is written. The tool keeps no extra privilege beyond the responses you handed it. The project file still contains them, which is the subject of the project-file lesson.
Diagram
Two known responses, then the words that differ
- Two rows
History has GET /api/invoices/1042 and GET /api/invoices/1048, both from Avery’s session.
- Send
Each response goes to Comparer. You compare responses, not an unrelated pair of hosts.
- Words
Word comparison highlights id, title, and the invoice status. The owner line stays the same.
- Note
You write the fields that moved and the fields that did not. The cookie is not one of them.
A diff you can explain
Inputs. A vendor response and a lab response, chosen because both were long.
Highlight. Almost every word, because the documents are different kinds of things.
Note. “They differ” is all you can say.
Inputs. Invoice 1042 and invoice 1048, same account, same route shape.
Highlight. id, title, and status. Owner matches on both sides.
Note. The note lists the three fields that changed and the owner that did not.
Left: GET /api/invoices/1042 Right: GET /api/invoices/1048 Same: owner avery@ledger.lab Differ: id, title, invoice status Skip: Cookie, Date, any request id that changes every time
Check yourself
1. You want to learn Comparer on Harbor Ledger. Which pair belongs in the tool?
2. Word comparison highlights the id, the title, and the invoice status. The owner line is not highlighted. What do you write?
3. The Date header is highlighted on every comparison you try. What is that header?