gopls/internal/golang: special handling for input context.Context

- Read and determine whether the first input parameter of function
or constructor is a context.Context through package name and name
comparison.
- Call the function or constructor with context.Background() but
honor is there is any renaming in foo.go or foo_test.go.
- Fix the issue where the constructor param is added to function
or method call.

For golang/vscode-go#1594

Change-Id: Ic1d145e65bc4b7cb34f637bab8ebdeccd36a33f9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/627355
Reviewed-by: Alan Donovan <[email protected]>
Auto-Submit: Hongxiang Jiang <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: h9jiang

gopls/internal/golang/addtest.go

@@ -457,12 +457,21 @@ func AddTestForFunc(ctx context.Context, snapshot *cache.Snapshot, loc protocol.
 
 	errorType := types.Universe.Lookup("error").Type()
 
-	// TODO(hxjiang): handle special case for ctx.Context input.
+	var isContextType = func(t types.Type) bool {
+		named, ok := t.(*types.Named)
+		if !ok {
+			return false
+		}
+		return named.Obj().Pkg().Path() == "context" && named.Obj().Name() == "Context"
+	}
+
 	for i := range sig.Params().Len() {
 		param := sig.Params().At(i)
 		name, typ := param.Name(), param.Type()
 		f := field{Type: types.TypeString(typ, qf)}
-		if name == "" || name == "_" {
+		if i == 0 && isContextType(typ) {
+			f.Value = qf(types.NewPackage("context", "context")) + ".Background()"
+		} else if name == "" || name == "_" {
 			f.Value = typesinternal.ZeroString(typ, qf)
 		} else {
 			f.Name = name
@@ -594,7 +603,9 @@ func AddTestForFunc(ctx context.Context, snapshot *cache.Snapshot, loc protocol.
 				param := constructor.Signature().Params().At(i)
 				name, typ := param.Name(), param.Type()
 				f := field{Type: types.TypeString(typ, qf)}
-				if name == "" || name == "_" {
+				if i == 0 && isContextType(typ) {
+					f.Value = qf(types.NewPackage("context", "context")) + ".Background()"
+				} else if name == "" || name == "_" {
 					f.Value = typesinternal.ZeroString(typ, qf)
 				} else {
 					f.Name = name

gopls/internal/test/marker/testdata/codeaction/addtest.txt

@@ -1319,3 +1319,100 @@ func (r *BarInputFunction) Method(one string, _ func(time.Time) *time.Time) {} /
 +    })
 +  }
 +}
+-- contextinput/contextinput.go --
+package main
+
+import "context"
+
+func Function(ctx context.Context, _, _ string) (out, out1, out2 string) {return "", "", ""} //@codeactionedit("Function", "source.addTest", function_context)
+
+type Foo struct {}
+
+func NewFoo(ctx context.Context) (*Foo, error) {return nil, nil}
+
+func (*Foo) Method(ctx context.Context, _, _ string)  (out, out1, out2 string) {return "", "", ""} //@codeactionedit("Method", "source.addTest", method_context)
+-- contextinput/contextinput_test.go --
+package main_test
+
+import renamedctx "context"
+
+var local renamedctx.Context
+
+-- @function_context/contextinput/contextinput_test.go --
+@@ -3 +3,3 @@
+-import renamedctx "context"
++import (
++	renamedctx "context"
++	"testing"
+@@ -5 +7,3 @@
++	"golang.org/lsptests/addtest/contextinput"
++)
++
+@@ -7 +12,26 @@
++
++func TestFunction(t *testing.T) {
++  tests := []struct {
++    name string // description of this test case
++    want string
++    want2 string
++    want3 string
++  }{
++    // TODO: Add test cases.
++  }
++  for _, tt := range tests {
++    t.Run(tt.name, func(t *testing.T) {
++      got, got2, got3 := main.Function(renamedctx.Background(), "", "")
++      // TODO: update the condition below to compare got with tt.want.
++      if true {
++        t.Errorf("Function() = %v, want %v", got, tt.want)
++      }
++      if true {
++        t.Errorf("Function() = %v, want %v", got2, tt.want2)
++      }
++      if true {
++        t.Errorf("Function() = %v, want %v", got3, tt.want3)
++      }
++    })
++  }
++}
+-- @method_context/contextinput/contextinput_test.go --
+@@ -3 +3,3 @@
+-import renamedctx "context"
++import (
++	renamedctx "context"
++	"testing"
+@@ -5 +7,3 @@
++	"golang.org/lsptests/addtest/contextinput"
++)
++
+@@ -7 +12,30 @@
++
++func TestFoo_Method(t *testing.T) {
++  tests := []struct {
++    name string // description of this test case
++    want string
++    want2 string
++    want3 string
++  }{
++    // TODO: Add test cases.
++  }
++  for _, tt := range tests {
++    t.Run(tt.name, func(t *testing.T) {
++      f, err := main.NewFoo(renamedctx.Background())
++      if err != nil {
++        t.Fatalf("could not contruct receiver type: %v", err)
++      }
++      got, got2, got3 := f.Method(renamedctx.Background(), "", "")
++      // TODO: update the condition below to compare got with tt.want.
++      if true {
++        t.Errorf("Method() = %v, want %v", got, tt.want)
++      }
++      if true {
++        t.Errorf("Method() = %v, want %v", got2, tt.want2)
++      }
++      if true {
++        t.Errorf("Method() = %v, want %v", got3, tt.want3)
++      }
++    })
++  }
++}