Fix prefix calculation when caching

- Fixes #745

Co-authored by: Zac Bergquist <zbergquist99@gmail.com>

lib/autocomplete/gocodeprovider.js

@@ -30,6 +30,7 @@ class GocodeProvider implements AutocompleteProvider {
   subscriptions: CompositeDisposable
   subscribers: Array<(Promise<any>) => void>
   currentSuggestions: Array<Suggestion>
+  currentPrefixStartIndex: number
   proposeBuiltins: bool
   unimportedPackages: bool
   selector: string
@@ -50,6 +51,7 @@ class GocodeProvider implements AutocompleteProvider {
     this.subscriptions = new CompositeDisposable()
     this.subscribers = []
     this.currentSuggestions = []
+    this.currentPrefixStartIndex = -1
     this.currentFile = ''
     this.currentRow = -1
     this.currentColumn = -1
@@ -179,12 +181,13 @@ class GocodeProvider implements AutocompleteProvider {
     this.currentFile = ''
     this.currentRow = -1
     this.currentColumn = -1
+    this.currentPrefixStartIndex = -1
   }
 
   getSuggestions (options: SuggestionRequest): Promise<Array<Suggestion>> {
     // only invoke gocode when a new word starts or the '.' char is entered
     // on all other keystrokes we just fuzzy filter the previous set of suggestions
-    let {prefix, bufferPosition, editor} = options
+    let {prefix, bufferPosition, editor, scopeDescriptor} = options
     prefix = prefix.trim()
     if (prefix === '') {
       if (!options.activatedManually) {
@@ -203,8 +206,9 @@ class GocodeProvider implements AutocompleteProvider {
     if (useCache && this.currentSuggestions.length && prefix.length > 0 && !prefix.endsWith('.')) {
       // fuzzy filter on this.currentSuggestions
       const p = new Promise((resolve) => {
+        const newPrefix = editor.getTextInBufferRange([[bufferPosition.row, bufferPosition.column - this.currentPrefixStartIndex - 1], bufferPosition])
         const fil = filter(this.currentSuggestions, prefix, {key: 'fuzzyMatch'})
-          .map(s => Object.assign({}, s, {replacementPrefix: prefix}))
+          .map(s => Object.assign({}, s, {replacementPrefix: newPrefix}))
         this.currentFile = editor.getPath()
         this.currentRow = bufferPosition.row
         this.currentColumn = bufferPosition.column
@@ -351,8 +355,8 @@ class GocodeProvider implements AutocompleteProvider {
     if (candidates[0] && candidates[0].class === 'PANIC' && candidates[0].type === 'PANIC' && candidates[0].name === 'PANIC') {
       this.bounceGocode()
     }
-    const numPrefix: number = res[0]
-    const prefix = editor.getTextInBufferRange([[position.row, position.column - numPrefix], position])
+    this.currentPrefixStartIndex = res[0]
+    const prefix = editor.getTextInBufferRange([[position.row, position.column - this.currentPrefixStartIndex], position])
     let suffix = ''
     try {
       suffix = editor.getTextInBufferRange([position, [position.row, position.column + 1]])

spec/autocomplete/gocodeprovider-spec.js

@@ -250,6 +250,78 @@ describe('gocodeprovider', () => {
     })
   })
 
+  describe('when the go-plus-issue-745 file is opened', () => {
+    let suggestions = null
+    beforeEach(() => {
+      waitsForPromise(() => {
+        return atom.workspace.open('go-plus-issue-745' + path.sep + 'main.go').then((e) => {
+          editor = e
+          editorView = atom.views.getView(editor)
+        })
+      })
+    })
+
+    it('calculates the prefix correctly', () => {
+      runs(() => {
+        expect(provider).toBeDefined()
+        expect(provider.getSuggestions).not.toHaveBeenCalled()
+        expect(editorView.querySelector('.autocomplete-plus')).not.toExist()
+        editor.setCursorBufferPosition([4, 10])
+        editor.backspace()
+        editor.backspace()
+        editor.backspace()
+        suggestions = null
+        suggestionsPromise = null
+        advanceClock(completionDelay)
+      })
+
+      runs(() => {
+        expect(provider.getSuggestions.calls.length).toBe(0)
+        expect(suggestionsPromise).toBeFalsy()
+        editor.insertText('t')
+        advanceClock(completionDelay)
+      })
+
+      waitsFor(() => {
+        return provider.getSuggestions.calls.length === 1 && suggestionsPromise !== null
+      })
+
+      waitsForPromise(() => {
+        return suggestionsPromise.then((s) => {
+          suggestions = s
+        })
+      })
+
+      runs(() => {
+        expect(provider.getSuggestions.calls.length).toBe(1)
+        expect(suggestionsPromise).toBeTruthy()
+        suggestionsPromise = null
+        editor.insertText('t')
+        advanceClock(completionDelay)
+      })
+
+      waitsFor(() => {
+        return provider.getSuggestions.calls.length === 2 && suggestionsPromise !== null
+      })
+
+      waitsForPromise(() => {
+        return suggestionsPromise.then((s) => {
+          suggestions = s
+        })
+      })
+
+      runs(() => {
+        expect(provider.getSuggestions).toHaveBeenCalled()
+        expect(provider.getSuggestions.calls.length).toBe(2)
+        expect(suggestions).toBeTruthy()
+        expect(suggestions.length).toBeGreaterThan(0)
+        expect(suggestions[0]).toBeTruthy()
+        expect(suggestions[0].text).toBe('net/http')
+        expect(suggestions[0].replacementPrefix).toBe('net/htt')
+      })
+    })
+  })
+
   describe('when the go-plus-issue-307 file is opened', () => {
     let suggestions = null
     beforeEach(() => {
@@ -410,7 +482,6 @@ describe('gocodeprovider', () => {
       runs(() => {
         expect(provider.getSuggestions.calls.length).toBe(0)
         expect(suggestionsPromise).toBeFalsy()
-        console.log('insert .')
 
         editor.insertText('.')
         advanceClock(completionDelay)

spec/fixtures/go-plus-issue-745/main.go

@@ -0,0 +1,10 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	fmt.Println(string(http.MethodGet))
+}