diff --git a/gopls/internal/regtest/bench/bench_test.go b/gopls/internal/regtest/bench/bench_test.go
index 22f157f471..dfe41f65b1 100644
--- a/gopls/internal/regtest/bench/bench_test.go
+++ b/gopls/internal/regtest/bench/bench_test.go
@@ -93,14 +93,14 @@ func TestBenchmarkSymbols(t *testing.T) {
 	}
 
 	opts := benchmarkOptions(symbolOptions.workdir)
-	conf := EditorConfig{}
+	settings := make(Settings)
 	if symbolOptions.matcher != "" {
-		conf.SymbolMatcher = &symbolOptions.matcher
+		settings["symbolMatcher"] = symbolOptions.matcher
 	}
 	if symbolOptions.style != "" {
-		conf.SymbolStyle = &symbolOptions.style
+		settings["symbolStyle"] = symbolOptions.style
 	}
-	opts = append(opts, conf)
+	opts = append(opts, settings)
 
 	WithOptions(opts...).Run(t, "", func(t *testing.T, env *Env) {
 		// We can't Await in this test, since we have disabled hooks. Instead, run
@@ -200,9 +200,10 @@ func TestBenchmarkDidChange(t *testing.T) {
 // Always run it in isolation since it measures global heap usage.
 //
 // Kubernetes example:
-//   $ go test -run=TestPrintMemStats -didchange_dir=$HOME/w/kubernetes
-//   TotalAlloc:      5766 MB
-//   HeapAlloc:       1984 MB
+//
+//	$ go test -run=TestPrintMemStats -didchange_dir=$HOME/w/kubernetes
+//	TotalAlloc:      5766 MB
+//	HeapAlloc:       1984 MB
 //
 // Both figures exhibit variance of less than 1%.
 func TestPrintMemStats(t *testing.T) {
diff --git a/gopls/internal/regtest/codelens/codelens_test.go b/gopls/internal/regtest/codelens/codelens_test.go
index a64f9c480a..12a7575415 100644
--- a/gopls/internal/regtest/codelens/codelens_test.go
+++ b/gopls/internal/regtest/codelens/codelens_test.go
@@ -63,9 +63,7 @@ const (
 	for _, test := range tests {
 		t.Run(test.label, func(t *testing.T) {
 			WithOptions(
-				EditorConfig{
-					CodeLenses: test.enabled,
-				},
+				Settings{"codelenses": test.enabled},
 			).Run(t, workspace, func(t *testing.T, env *Env) {
 				env.OpenFile("lib.go")
 				lens := env.CodeLens("lib.go")
@@ -308,10 +306,11 @@ func main() {
 }
 `
 	WithOptions(
-		EditorConfig{
-			CodeLenses: map[string]bool{
+		Settings{
+			"codelenses": map[string]bool{
 				"gc_details": true,
-			}},
+			},
+		},
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		env.OpenFile("main.go")
 		env.ExecuteCodeLensCommand("main.go", command.GCDetails)
diff --git a/gopls/internal/regtest/completion/completion_test.go b/gopls/internal/regtest/completion/completion_test.go
index 1ffb0000d3..51a54c4973 100644
--- a/gopls/internal/regtest/completion/completion_test.go
+++ b/gopls/internal/regtest/completion/completion_test.go
@@ -529,7 +529,7 @@ func main() {
 }
 `
 	WithOptions(
-		EditorConfig{WindowsLineEndings: true},
+		WindowsLineEndings(),
 	).Run(t, src, func(t *testing.T, env *Env) {
 		// Trigger unimported completions for the example.com/blah package.
 		env.OpenFile("main.go")
diff --git a/gopls/internal/regtest/debug/debug_test.go b/gopls/internal/regtest/debug/debug_test.go
index d60b3f780d..d01d44ed98 100644
--- a/gopls/internal/regtest/debug/debug_test.go
+++ b/gopls/internal/regtest/debug/debug_test.go
@@ -21,11 +21,7 @@ func TestBugNotification(t *testing.T) {
 	// server.
 	WithOptions(
 		Modes(Singleton), // must be in-process to receive the bug report below
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"showBugReports": true,
-			},
-		},
+		Settings{"showBugReports": true},
 	).Run(t, "", func(t *testing.T, env *Env) {
 		const desc = "got a bug"
 		bug.Report(desc, nil)
diff --git a/gopls/internal/regtest/diagnostics/diagnostics_test.go b/gopls/internal/regtest/diagnostics/diagnostics_test.go
index 6f5db4cd41..b9dc2d434b 100644
--- a/gopls/internal/regtest/diagnostics/diagnostics_test.go
+++ b/gopls/internal/regtest/diagnostics/diagnostics_test.go
@@ -471,12 +471,11 @@ func _() {
 }
 `
 	WithOptions(
-		EditorConfig{
-			Env: map[string]string{
-				"GOPATH":      "",
-				"GO111MODULE": "off",
-			},
-		}).Run(t, files, func(t *testing.T, env *Env) {
+		EnvVars{
+			"GOPATH":      "",
+			"GO111MODULE": "off",
+		},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("main.go")
 		env.Await(env.DiagnosticAtRegexp("main.go", "fmt"))
 		env.SaveBuffer("main.go")
@@ -500,8 +499,9 @@ package x
 
 var X = 0
 `
-	editorConfig := EditorConfig{Env: map[string]string{"GOFLAGS": "-tags=foo"}}
-	WithOptions(editorConfig).Run(t, files, func(t *testing.T, env *Env) {
+	WithOptions(
+		EnvVars{"GOFLAGS": "-tags=foo"},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("main.go")
 		env.OrganizeImports("main.go")
 		env.Await(EmptyDiagnostics("main.go"))
@@ -573,9 +573,9 @@ hi mom
 `
 	for _, go111module := range []string{"on", "off", ""} {
 		t.Run(fmt.Sprintf("GO111MODULE_%v", go111module), func(t *testing.T) {
-			WithOptions(EditorConfig{
-				Env: map[string]string{"GO111MODULE": go111module},
-			}).Run(t, files, func(t *testing.T, env *Env) {
+			WithOptions(
+				EnvVars{"GO111MODULE": go111module},
+			).Run(t, files, func(t *testing.T, env *Env) {
 				env.Await(
 					NoOutstandingWork(),
 				)
@@ -605,11 +605,7 @@ func main() {
 `
 	WithOptions(
 		InGOPATH(),
-		EditorConfig{
-			Env: map[string]string{
-				"GO111MODULE": "off",
-			},
-		},
+		EnvVars{"GO111MODULE": "off"},
 	).Run(t, collision, func(t *testing.T, env *Env) {
 		env.OpenFile("x/x.go")
 		env.Await(
@@ -1236,7 +1232,7 @@ func main() {
 	})
 	WithOptions(
 		WorkspaceFolders("a"),
-		LimitWorkspaceScope(),
+		Settings{"expandWorkspaceToModule": false},
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		env.OpenFile("a/main.go")
 		env.Await(
@@ -1267,11 +1263,7 @@ func main() {
 `
 
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"staticcheck": true,
-			},
-		},
+		Settings{"staticcheck": true},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("main.go")
 		var d protocol.PublishDiagnosticsParams
@@ -1381,9 +1373,7 @@ func b(c bytes.Buffer) {
 }
 `
 	WithOptions(
-		EditorConfig{
-			AllExperiments: true,
-		},
+		Settings{"allExperiments": true},
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		// Confirm that the setting doesn't cause any warnings.
 		env.Await(NoShowMessage())
@@ -1495,11 +1485,7 @@ package foo_
 	WithOptions(
 		ProxyFiles(proxy),
 		InGOPATH(),
-		EditorConfig{
-			Env: map[string]string{
-				"GO111MODULE": "off",
-			},
-		},
+		EnvVars{"GO111MODULE": "off"},
 	).Run(t, contents, func(t *testing.T, env *Env) {
 		// Simulate typing character by character.
 		env.OpenFile("foo/foo_test.go")
@@ -1698,9 +1684,7 @@ import (
 	t.Run("GOPATH", func(t *testing.T) {
 		WithOptions(
 			InGOPATH(),
-			EditorConfig{
-				Env: map[string]string{"GO111MODULE": "off"},
-			},
+			EnvVars{"GO111MODULE": "off"},
 			Modes(Singleton),
 		).Run(t, mod, func(t *testing.T, env *Env) {
 			env.Await(
@@ -1729,11 +1713,7 @@ package b
 		t.Run("GO111MODULE="+go111module, func(t *testing.T) {
 			WithOptions(
 				Modes(Singleton),
-				EditorConfig{
-					Env: map[string]string{
-						"GO111MODULE": go111module,
-					},
-				},
+				EnvVars{"GO111MODULE": go111module},
 			).Run(t, modules, func(t *testing.T, env *Env) {
 				env.OpenFile("a/a.go")
 				env.OpenFile("b/go.mod")
@@ -1750,11 +1730,7 @@ package b
 	t.Run("GOPATH_GO111MODULE_auto", func(t *testing.T) {
 		WithOptions(
 			Modes(Singleton),
-			EditorConfig{
-				Env: map[string]string{
-					"GO111MODULE": "auto",
-				},
-			},
+			EnvVars{"GO111MODULE": "auto"},
 			InGOPATH(),
 		).Run(t, modules, func(t *testing.T, env *Env) {
 			env.OpenFile("a/a.go")
@@ -2026,9 +2002,7 @@ package a
 func Hello() {}
 `
 	WithOptions(
-		EditorConfig{
-			ExperimentalUseInvalidMetadata: true,
-		},
+		Settings{"experimentalUseInvalidMetadata": true},
 		Modes(Singleton),
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		env.OpenFile("go.mod")
@@ -2082,9 +2056,7 @@ package main
 func _() {}
 `
 	WithOptions(
-		EditorConfig{
-			ExperimentalUseInvalidMetadata: true,
-		},
+		Settings{"experimentalUseInvalidMetadata": true},
 		// ExperimentalWorkspaceModule has a different failure mode for this
 		// case.
 		Modes(Singleton),
diff --git a/gopls/internal/regtest/inlayhints/inlayhints_test.go b/gopls/internal/regtest/inlayhints/inlayhints_test.go
index a7cbe65731..1ca1dfbc09 100644
--- a/gopls/internal/regtest/inlayhints/inlayhints_test.go
+++ b/gopls/internal/regtest/inlayhints/inlayhints_test.go
@@ -56,10 +56,8 @@ const (
 	for _, test := range tests {
 		t.Run(test.label, func(t *testing.T) {
 			WithOptions(
-				EditorConfig{
-					Settings: map[string]interface{}{
-						"hints": test.enabled,
-					},
+				Settings{
+					"hints": test.enabled,
 				},
 			).Run(t, workspace, func(t *testing.T, env *Env) {
 				env.OpenFile("lib.go")
diff --git a/gopls/internal/regtest/misc/configuration_test.go b/gopls/internal/regtest/misc/configuration_test.go
index d9cce96a43..9629a2382e 100644
--- a/gopls/internal/regtest/misc/configuration_test.go
+++ b/gopls/internal/regtest/misc/configuration_test.go
@@ -9,7 +9,6 @@ import (
 
 	. "golang.org/x/tools/internal/lsp/regtest"
 
-	"golang.org/x/tools/internal/lsp/fake"
 	"golang.org/x/tools/internal/testenv"
 )
 
@@ -40,12 +39,11 @@ var FooErr = errors.New("foo")
 			env.DoneWithOpen(),
 			NoDiagnostics("a/a.go"),
 		)
-		cfg := &fake.EditorConfig{}
-		*cfg = env.Editor.Config
+		cfg := env.Editor.Config()
 		cfg.Settings = map[string]interface{}{
 			"staticcheck": true,
 		}
-		env.ChangeConfiguration(t, cfg)
+		env.ChangeConfiguration(cfg)
 		env.Await(
 			DiagnosticAt("a/a.go", 5, 4),
 		)
@@ -70,11 +68,9 @@ import "errors"
 var FooErr = errors.New("foo")
 `
 
-	WithOptions(EditorConfig{
-		Settings: map[string]interface{}{
-			"staticcheck": true,
-		},
-	}).Run(t, files, func(t *testing.T, env *Env) {
+	WithOptions(
+		Settings{"staticcheck": true},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.Await(ShownMessage("staticcheck is not supported"))
 	})
 }
diff --git a/gopls/internal/regtest/misc/definition_test.go b/gopls/internal/regtest/misc/definition_test.go
index 2f5a54820d..b71cf23107 100644
--- a/gopls/internal/regtest/misc/definition_test.go
+++ b/gopls/internal/regtest/misc/definition_test.go
@@ -162,9 +162,7 @@ func main() {}
 	} {
 		t.Run(tt.importShortcut, func(t *testing.T) {
 			WithOptions(
-				EditorConfig{
-					ImportShortcut: tt.importShortcut,
-				},
+				Settings{"importShortcut": tt.importShortcut},
 			).Run(t, mod, func(t *testing.T, env *Env) {
 				env.OpenFile("main.go")
 				file, pos := env.GoToDefinition("main.go", env.RegexpSearch("main.go", `"fmt"`))
diff --git a/gopls/internal/regtest/misc/formatting_test.go b/gopls/internal/regtest/misc/formatting_test.go
index 75d8f62245..71b8cadab4 100644
--- a/gopls/internal/regtest/misc/formatting_test.go
+++ b/gopls/internal/regtest/misc/formatting_test.go
@@ -352,10 +352,8 @@ const Bar = 42
 `
 
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"gofumpt": true,
-			},
+		Settings{
+			"gofumpt": true,
 		},
 	).Run(t, input, func(t *testing.T, env *Env) {
 		env.OpenFile("foo.go")
diff --git a/gopls/internal/regtest/misc/imports_test.go b/gopls/internal/regtest/misc/imports_test.go
index 1250e78e77..c0e213e9ae 100644
--- a/gopls/internal/regtest/misc/imports_test.go
+++ b/gopls/internal/regtest/misc/imports_test.go
@@ -153,9 +153,8 @@ var _, _ = x.X, y.Y
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(modcache)
-	editorConfig := EditorConfig{Env: map[string]string{"GOMODCACHE": modcache}}
 	WithOptions(
-		editorConfig,
+		EnvVars{"GOMODCACHE": modcache},
 		ProxyFiles(proxy),
 	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("main.go")
diff --git a/gopls/internal/regtest/misc/link_test.go b/gopls/internal/regtest/misc/link_test.go
index e84f6377ee..1005de9a24 100644
--- a/gopls/internal/regtest/misc/link_test.go
+++ b/gopls/internal/regtest/misc/link_test.go
@@ -75,7 +75,9 @@ const Hello = "Hello"
 		}
 
 		// Then change the environment to make these links private.
-		env.ChangeEnv(map[string]string{"GOPRIVATE": "import.test"})
+		cfg := env.Editor.Config()
+		cfg.Env = map[string]string{"GOPRIVATE": "import.test"}
+		env.ChangeConfiguration(cfg)
 
 		// Finally, verify that the links are gone.
 		content, _ = env.Hover("main.go", env.RegexpSearch("main.go", "pkg.Hello"))
diff --git a/gopls/internal/regtest/misc/semantictokens_test.go b/gopls/internal/regtest/misc/semantictokens_test.go
index 79507876a6..dca2b8e751 100644
--- a/gopls/internal/regtest/misc/semantictokens_test.go
+++ b/gopls/internal/regtest/misc/semantictokens_test.go
@@ -26,9 +26,7 @@ func main() {}
 `
 	WithOptions(
 		Modes(Singleton),
-		EditorConfig{
-			AllExperiments: true,
-		},
+		Settings{"allExperiments": true},
 	).Run(t, src, func(t *testing.T, env *Env) {
 		params := &protocol.SemanticTokensParams{}
 		const badURI = "http://foo"
diff --git a/gopls/internal/regtest/misc/settings_test.go b/gopls/internal/regtest/misc/settings_test.go
index 7704c3c043..62d3d90316 100644
--- a/gopls/internal/regtest/misc/settings_test.go
+++ b/gopls/internal/regtest/misc/settings_test.go
@@ -24,11 +24,7 @@ func main() {
 `
 
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"directoryFilters": []string{""},
-			},
-		},
+		Settings{"directoryFilters": []string{""}},
 	).Run(t, src, func(t *testing.T, env *Env) {
 		// No need to do anything. Issue golang/go#51843 is triggered by the empty
 		// directory filter above.
diff --git a/gopls/internal/regtest/misc/shared_test.go b/gopls/internal/regtest/misc/shared_test.go
index a6b0cd87ef..6b5acd02f7 100644
--- a/gopls/internal/regtest/misc/shared_test.go
+++ b/gopls/internal/regtest/misc/shared_test.go
@@ -30,7 +30,7 @@ func runShared(t *testing.T, testFunc func(env1 *Env, env2 *Env)) {
 	WithOptions(Modes(modes)).Run(t, sharedProgram, func(t *testing.T, env1 *Env) {
 		// Create a second test session connected to the same workspace and server
 		// as the first.
-		env2, cleanup := NewEnv(env1.Ctx, t, env1.Sandbox, env1.Server, env1.Editor.Config, true)
+		env2, cleanup := NewEnv(env1.Ctx, t, env1.Sandbox, env1.Server, env1.Editor.Config(), true)
 		defer cleanup()
 		env2.Await(InitialWorkspaceLoad)
 		testFunc(env1, env2)
diff --git a/gopls/internal/regtest/misc/staticcheck_test.go b/gopls/internal/regtest/misc/staticcheck_test.go
index 94bb39903a..6f1bda3506 100644
--- a/gopls/internal/regtest/misc/staticcheck_test.go
+++ b/gopls/internal/regtest/misc/staticcheck_test.go
@@ -60,11 +60,9 @@ func testGenerics[P *T, T any](p P) {
 var FooErr error = errors.New("foo")
 `
 
-	WithOptions(EditorConfig{
-		Settings: map[string]interface{}{
-			"staticcheck": true,
-		},
-	}).Run(t, files, func(t *testing.T, env *Env) {
+	WithOptions(
+		Settings{"staticcheck": true},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("a/a.go")
 		env.Await(
 			env.DiagnosticAtRegexpFromSource("a/a.go", "sort.Slice", "sortslice"),
diff --git a/gopls/internal/regtest/misc/workspace_symbol_test.go b/gopls/internal/regtest/misc/workspace_symbol_test.go
index a21d47312d..2dc3a1b10d 100644
--- a/gopls/internal/regtest/misc/workspace_symbol_test.go
+++ b/gopls/internal/regtest/misc/workspace_symbol_test.go
@@ -72,9 +72,7 @@ const (
 
 	var symbolMatcher = string(source.SymbolFastFuzzy)
 	WithOptions(
-		EditorConfig{
-			SymbolMatcher: &symbolMatcher,
-		},
+		Settings{"symbolMatcher": symbolMatcher},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		want := []string{
 			"Foo",    // prefer exact segment matches first
@@ -105,9 +103,7 @@ const (
 
 	var symbolMatcher = string(source.SymbolFastFuzzy)
 	WithOptions(
-		EditorConfig{
-			SymbolMatcher: &symbolMatcher,
-		},
+		Settings{"symbolMatcher": symbolMatcher},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		compareSymbols(t, env.WorkspaceSymbol("ABC"), []string{"ABC", "AxxBxxCxx"})
 		compareSymbols(t, env.WorkspaceSymbol("'ABC"), []string{"ABC"})
diff --git a/gopls/internal/regtest/modfile/modfile_test.go b/gopls/internal/regtest/modfile/modfile_test.go
index 93d4325304..c0bef833f4 100644
--- a/gopls/internal/regtest/modfile/modfile_test.go
+++ b/gopls/internal/regtest/modfile/modfile_test.go
@@ -740,11 +740,7 @@ func main() {
 }
 `
 	WithOptions(
-		EditorConfig{
-			Env: map[string]string{
-				"GOFLAGS": "-mod=readonly",
-			},
-		},
+		EnvVars{"GOFLAGS": "-mod=readonly"},
 		ProxyFiles(proxy),
 		Modes(Singleton),
 	).Run(t, mod, func(t *testing.T, env *Env) {
@@ -830,9 +826,7 @@ func main() {
 `
 	WithOptions(
 		ProxyFiles(workspaceProxy),
-		EditorConfig{
-			BuildFlags: []string{"-tags", "bob"},
-		},
+		Settings{"buildFlags": []string{"-tags", "bob"}},
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		env.Await(
 			env.DiagnosticAtRegexp("main.go", `"example.com/blah"`),
diff --git a/gopls/internal/regtest/template/template_test.go b/gopls/internal/regtest/template/template_test.go
index 9489e9bf7f..0fdc3bda6f 100644
--- a/gopls/internal/regtest/template/template_test.go
+++ b/gopls/internal/regtest/template/template_test.go
@@ -35,11 +35,9 @@ go 1.17
 {{end}}
 `
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"templateExtensions": []string{"tmpl"},
-				"semanticTokens":     true,
-			},
+		Settings{
+			"templateExtensions": []string{"tmpl"},
+			"semanticTokens":     true,
 		},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		var p protocol.SemanticTokensParams
@@ -66,11 +64,9 @@ Hello {{}} <-- missing body
 {{end}}
 `
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"templateExtensions": []string{"tmpl"},
-				"semanticTokens":     true,
-			},
+		Settings{
+			"templateExtensions": []string{"tmpl"},
+			"semanticTokens":     true,
 		},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		// TODO: can we move this diagnostic onto {{}}?
@@ -112,11 +108,9 @@ B {{}} <-- missing body
 `
 
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"templateExtensions": []string{"tmpl"},
-			},
-			DirectoryFilters: []string{"-b"},
+		Settings{
+			"directoryFilters":   []string{"-b"},
+			"templateExtensions": []string{"tmpl"},
 		},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		env.Await(
@@ -184,10 +178,8 @@ go 1.12
 `
 
 	WithOptions(
-		EditorConfig{
-			Settings: map[string]interface{}{
-				"templateExtensions": []string{"tmpl", "gotmpl"},
-			},
+		Settings{
+			"templateExtensions": []string{"tmpl", "gotmpl"},
 		},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("a.tmpl")
diff --git a/gopls/internal/regtest/watch/watch_test.go b/gopls/internal/regtest/watch/watch_test.go
index e66d08ab12..04414f6b74 100644
--- a/gopls/internal/regtest/watch/watch_test.go
+++ b/gopls/internal/regtest/watch/watch_test.go
@@ -389,9 +389,9 @@ func _() {
 package a
 `
 	t.Run("close then delete", func(t *testing.T) {
-		WithOptions(EditorConfig{
-			VerboseOutput: true,
-		}).Run(t, pkg, func(t *testing.T, env *Env) {
+		WithOptions(
+			Settings{"verboseOutput": true},
+		).Run(t, pkg, func(t *testing.T, env *Env) {
 			env.OpenFile("a/a.go")
 			env.OpenFile("a/a_unneeded.go")
 			env.Await(
@@ -424,7 +424,7 @@ package a
 
 	t.Run("delete then close", func(t *testing.T) {
 		WithOptions(
-			EditorConfig{VerboseOutput: true},
+			Settings{"verboseOutput": true},
 		).Run(t, pkg, func(t *testing.T, env *Env) {
 			env.OpenFile("a/a.go")
 			env.OpenFile("a/a_unneeded.go")
@@ -620,11 +620,7 @@ func main() {
 `
 	WithOptions(
 		InGOPATH(),
-		EditorConfig{
-			Env: map[string]string{
-				"GO111MODULE": "auto",
-			},
-		},
+		EnvVars{"GO111MODULE": "auto"},
 		Modes(Experimental), // module is in a subdirectory
 	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("foo/main.go")
@@ -663,11 +659,7 @@ func main() {
 `
 	WithOptions(
 		InGOPATH(),
-		EditorConfig{
-			Env: map[string]string{
-				"GO111MODULE": "auto",
-			},
-		},
+		EnvVars{"GO111MODULE": "auto"},
 	).Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("foo/main.go")
 		env.RemoveWorkspaceFile("foo/go.mod")
diff --git a/gopls/internal/regtest/workspace/workspace_test.go b/gopls/internal/regtest/workspace/workspace_test.go
index 9e4b85fced..7eafaf191d 100644
--- a/gopls/internal/regtest/workspace/workspace_test.go
+++ b/gopls/internal/regtest/workspace/workspace_test.go
@@ -1036,10 +1036,10 @@ package exclude
 
 const _ = Nonexistant
 `
-	cfg := EditorConfig{
-		DirectoryFilters: []string{"-exclude"},
-	}
-	WithOptions(cfg).Run(t, files, func(t *testing.T, env *Env) {
+
+	WithOptions(
+		Settings{"directoryFilters": []string{"-exclude"}},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.Await(NoDiagnostics("exclude/x.go"))
 	})
 }
@@ -1064,10 +1064,9 @@ const _ = Nonexistant // should be ignored, since this is a non-workspace packag
 const X = 1
 `
 
-	cfg := EditorConfig{
-		DirectoryFilters: []string{"-exclude"},
-	}
-	WithOptions(cfg).Run(t, files, func(t *testing.T, env *Env) {
+	WithOptions(
+		Settings{"directoryFilters": []string{"-exclude"}},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.Await(
 			NoDiagnostics("exclude/exclude.go"), // filtered out
 			NoDiagnostics("include/include.go"), // successfully builds
@@ -1114,10 +1113,11 @@ go 1.12
 -- exclude.com@v1.0.0/exclude.go --
 package exclude
 `
-	cfg := EditorConfig{
-		DirectoryFilters: []string{"-exclude"},
-	}
-	WithOptions(cfg, Modes(Experimental), ProxyFiles(proxy)).Run(t, files, func(t *testing.T, env *Env) {
+	WithOptions(
+		Modes(Experimental),
+		ProxyFiles(proxy),
+		Settings{"directoryFilters": []string{"-exclude"}},
+	).Run(t, files, func(t *testing.T, env *Env) {
 		env.Await(env.DiagnosticAtRegexp("include/include.go", `exclude.(X)`))
 	})
 }
@@ -1204,9 +1204,7 @@ go 1.12
 package main
 `
 	WithOptions(
-		EditorConfig{Env: map[string]string{
-			"GOPATH": filepath.FromSlash("$SANDBOX_WORKDIR/gopath"),
-		}},
+		EnvVars{"GOPATH": filepath.FromSlash("$SANDBOX_WORKDIR/gopath")},
 		Modes(Singleton),
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		env.Await(
diff --git a/internal/lsp/fake/client.go b/internal/lsp/fake/client.go
index fdc67a6cc6..4c5f2a2e1b 100644
--- a/internal/lsp/fake/client.go
+++ b/internal/lsp/fake/client.go
@@ -77,7 +77,7 @@ func (c *Client) Configuration(_ context.Context, p *protocol.ParamConfiguration
 		if item.Section != "gopls" {
 			continue
 		}
-		results[i] = c.editor.configuration()
+		results[i] = c.editor.settings()
 	}
 	return results, nil
 }
diff --git a/internal/lsp/fake/editor.go b/internal/lsp/fake/editor.go
index 0fc99a0498..240e35cffa 100644
--- a/internal/lsp/fake/editor.go
+++ b/internal/lsp/fake/editor.go
@@ -25,7 +25,6 @@ import (
 // Editor is a fake editor client.  It keeps track of client state and can be
 // used for writing LSP tests.
 type Editor struct {
-	Config EditorConfig
 
 	// Server, client, and sandbox are concurrency safe and written only
 	// at construction time, so do not require synchronization.
@@ -35,13 +34,10 @@ type Editor struct {
 	sandbox    *Sandbox
 	defaultEnv map[string]string
 
-	// Since this editor is intended just for testing, we use very coarse
-	// locking.
-	mu sync.Mutex
-	// Editor state.
-	buffers map[string]buffer
-	// Capabilities / Options
-	serverCapabilities protocol.ServerCapabilities
+	mu                 sync.Mutex                  // guards config, buffers, serverCapabilities
+	config             EditorConfig                // editor configuration
+	buffers            map[string]buffer           // open buffers
+	serverCapabilities protocol.ServerCapabilities // capabilities / options
 
 	// Call metrics for the purpose of expectations. This is done in an ad-hoc
 	// manner for now. Perhaps in the future we should do something more
@@ -77,21 +73,11 @@ func (b buffer) text() string {
 //
 // The zero value for EditorConfig should correspond to its defaults.
 type EditorConfig struct {
-	Env        map[string]string
-	BuildFlags []string
-
-	// CodeLenses is a map defining whether codelens are enabled, keyed by the
-	// codeLens command. CodeLenses which are not present in this map are left in
-	// their default state.
-	CodeLenses map[string]bool
-
-	// SymbolMatcher is the config associated with the "symbolMatcher" gopls
-	// config option.
-	SymbolMatcher, SymbolStyle *string
-
-	// LimitWorkspaceScope is true if the user does not want to expand their
-	// workspace scope to the entire module.
-	LimitWorkspaceScope bool
+	// Env holds environment variables to apply on top of the default editor
+	// environment. When applying these variables, the special string
+	// $SANDBOX_WORKDIR is replaced by the absolute path to the sandbox working
+	// directory.
+	Env map[string]string
 
 	// WorkspaceFolders is the workspace folders to configure on the LSP server,
 	// relative to the sandbox workdir.
@@ -101,14 +87,6 @@ type EditorConfig struct {
 	// To explicitly send no workspace folders, use an empty (non-nil) slice.
 	WorkspaceFolders []string
 
-	// AllExperiments sets the "allExperiments" configuration, which enables
-	// all of gopls's opt-in settings.
-	AllExperiments bool
-
-	// Whether to send the current process ID, for testing data that is joined to
-	// the PID. This can only be set by one test.
-	SendPID bool
-
 	// Whether to edit files with windows line endings.
 	WindowsLineEndings bool
 
@@ -120,14 +98,8 @@ type EditorConfig struct {
 	//  "gotmpl" -> ".*tmpl"
 	FileAssociations map[string]string
 
-	// Settings holds arbitrary additional settings to apply to the gopls config.
-	// TODO(rfindley): replace existing EditorConfig fields with Settings.
+	// Settings holds user-provided configuration for the LSP server.
 	Settings map[string]interface{}
-
-	ImportShortcut                 string
-	DirectoryFilters               []string
-	VerboseOutput                  bool
-	ExperimentalUseInvalidMetadata bool
 }
 
 // NewEditor Creates a new Editor.
@@ -136,7 +108,7 @@ func NewEditor(sandbox *Sandbox, config EditorConfig) *Editor {
 		buffers:    make(map[string]buffer),
 		sandbox:    sandbox,
 		defaultEnv: sandbox.GoEnv(),
-		Config:     config,
+		config:     config,
 	}
 }
 
@@ -155,7 +127,7 @@ func (e *Editor) Connect(ctx context.Context, conn jsonrpc2.Conn, hooks ClientHo
 		protocol.Handlers(
 			protocol.ClientHandler(e.client,
 				jsonrpc2.MethodNotFound)))
-	if err := e.initialize(ctx, e.Config.WorkspaceFolders); err != nil {
+	if err := e.initialize(ctx, e.config.WorkspaceFolders); err != nil {
 		return nil, err
 	}
 	e.sandbox.Workdir.AddWatcher(e.onFileChanges)
@@ -213,65 +185,47 @@ func (e *Editor) Client() *Client {
 	return e.client
 }
 
-func (e *Editor) overlayEnv() map[string]string {
+// settings builds the settings map for use in LSP settings
+// RPCs.
+func (e *Editor) settings() map[string]interface{} {
+	e.mu.Lock()
+	defer e.mu.Unlock()
 	env := make(map[string]string)
 	for k, v := range e.defaultEnv {
+		env[k] = v
+	}
+	for k, v := range e.config.Env {
+		env[k] = v
+	}
+	for k, v := range env {
 		v = strings.ReplaceAll(v, "$SANDBOX_WORKDIR", e.sandbox.Workdir.RootURI().SpanURI().Filename())
 		env[k] = v
 	}
-	for k, v := range e.Config.Env {
-		v = strings.ReplaceAll(v, "$SANDBOX_WORKDIR", e.sandbox.Workdir.RootURI().SpanURI().Filename())
-		env[k] = v
-	}
-	return env
-}
 
-func (e *Editor) configuration() map[string]interface{} {
-	config := map[string]interface{}{
+	settings := map[string]interface{}{
+		"env": env,
+
+		// Use verbose progress reporting so that regtests can assert on
+		// asynchronous operations being completed (such as diagnosing a snapshot).
 		"verboseWorkDoneProgress": true,
-		"env":                     e.overlayEnv(),
-		"expandWorkspaceToModule": !e.Config.LimitWorkspaceScope,
-		"completionBudget":        "10s",
+
+		// Set a generous completion budget, so that tests don't flake because
+		// completions are too slow.
+		"completionBudget": "10s",
+
+		// Shorten the diagnostic delay to speed up test execution (else we'd add
+		// the default delay to each assertion about diagnostics)
+		"diagnosticsDelay": "10ms",
 	}
 
-	for k, v := range e.Config.Settings {
-		config[k] = v
+	for k, v := range e.config.Settings {
+		if k == "env" {
+			panic("must not provide env via the EditorConfig.Settings field: use the EditorConfig.Env field instead")
+		}
+		settings[k] = v
 	}
 
-	if e.Config.BuildFlags != nil {
-		config["buildFlags"] = e.Config.BuildFlags
-	}
-	if e.Config.DirectoryFilters != nil {
-		config["directoryFilters"] = e.Config.DirectoryFilters
-	}
-	if e.Config.ExperimentalUseInvalidMetadata {
-		config["experimentalUseInvalidMetadata"] = true
-	}
-	if e.Config.CodeLenses != nil {
-		config["codelenses"] = e.Config.CodeLenses
-	}
-	if e.Config.SymbolMatcher != nil {
-		config["symbolMatcher"] = *e.Config.SymbolMatcher
-	}
-	if e.Config.SymbolStyle != nil {
-		config["symbolStyle"] = *e.Config.SymbolStyle
-	}
-	if e.Config.AllExperiments {
-		config["allExperiments"] = true
-	}
-
-	if e.Config.VerboseOutput {
-		config["verboseOutput"] = true
-	}
-
-	if e.Config.ImportShortcut != "" {
-		config["importShortcut"] = e.Config.ImportShortcut
-	}
-
-	config["diagnosticsDelay"] = "10ms"
-
-	// ExperimentalWorkspaceModule is only set as a mode, not a configuration.
-	return config
+	return settings
 }
 
 func (e *Editor) initialize(ctx context.Context, workspaceFolders []string) error {
@@ -293,10 +247,7 @@ func (e *Editor) initialize(ctx context.Context, workspaceFolders []string) erro
 	params.Capabilities.Window.WorkDoneProgress = true
 	// TODO: set client capabilities
 	params.Capabilities.TextDocument.Completion.CompletionItem.TagSupport.ValueSet = []protocol.CompletionItemTag{protocol.ComplDeprecated}
-	params.InitializationOptions = e.configuration()
-	if e.Config.SendPID {
-		params.ProcessID = int32(os.Getpid())
-	}
+	params.InitializationOptions = e.settings()
 
 	params.Capabilities.TextDocument.Completion.CompletionItem.SnippetSupport = true
 	params.Capabilities.TextDocument.SemanticTokens.Requests.Full = true
@@ -397,20 +348,21 @@ func (e *Editor) CreateBuffer(ctx context.Context, path, content string) error {
 }
 
 func (e *Editor) createBuffer(ctx context.Context, path string, dirty bool, content string) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
 	buf := buffer{
-		windowsLineEndings: e.Config.WindowsLineEndings,
+		windowsLineEndings: e.config.WindowsLineEndings,
 		version:            1,
 		path:               path,
 		lines:              lines(content),
 		dirty:              dirty,
 	}
-	e.mu.Lock()
-	defer e.mu.Unlock()
 	e.buffers[path] = buf
 
 	item := protocol.TextDocumentItem{
 		URI:        e.sandbox.Workdir.URI(buf.path),
-		LanguageID: e.languageID(buf.path),
+		LanguageID: languageID(buf.path, e.config.FileAssociations),
 		Version:    int32(buf.version),
 		Text:       buf.text(),
 	}
@@ -436,9 +388,11 @@ var defaultFileAssociations = map[string]*regexp.Regexp{
 	"gotmpl":  regexp.MustCompile(`^.*tmpl$`),
 }
 
-func (e *Editor) languageID(p string) string {
+// languageID returns the language identifier for the path p given the user
+// configured fileAssociations.
+func languageID(p string, fileAssociations map[string]string) string {
 	base := path.Base(p)
-	for lang, re := range e.Config.FileAssociations {
+	for lang, re := range fileAssociations {
 		re := regexp.MustCompile(re)
 		if re.MatchString(base) {
 			return lang
@@ -1205,6 +1159,30 @@ func (e *Editor) applyProtocolEdit(ctx context.Context, change protocol.TextDocu
 	return e.EditBuffer(ctx, path, fakeEdits)
 }
 
+// Config returns the current editor configuration.
+func (e *Editor) Config() EditorConfig {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	return e.config
+}
+
+// ChangeConfiguration sets the new editor configuration, and if applicable
+// sends a didChangeConfiguration notification.
+//
+// An error is returned if the change notification failed to send.
+func (e *Editor) ChangeConfiguration(ctx context.Context, newConfig EditorConfig) error {
+	e.mu.Lock()
+	e.config = newConfig
+	e.mu.Unlock() // don't hold e.mu during server calls
+	if e.Server != nil {
+		var params protocol.DidChangeConfigurationParams // empty: gopls ignores the Settings field
+		if err := e.Server.DidChangeConfiguration(ctx, &params); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // CodeAction executes a codeAction request on the server.
 func (e *Editor) CodeAction(ctx context.Context, path string, rng *protocol.Range, diagnostics []protocol.Diagnostic) ([]protocol.CodeAction, error) {
 	if e.Server == nil {
diff --git a/internal/lsp/regtest/env.go b/internal/lsp/regtest/env.go
index a37cbf6661..8960a0dc91 100644
--- a/internal/lsp/regtest/env.go
+++ b/internal/lsp/regtest/env.go
@@ -111,7 +111,11 @@ type condition struct {
 // NewEnv creates a new test environment using the given scratch environment
 // and gopls server.
 //
-// The resulting func must be called to close the jsonrpc2 connection.
+// The resulting cleanup func must be called to close the jsonrpc2 connection.
+//
+// TODO(rfindley): this function provides questionable value. Consider
+// refactoring to move things like creating the server outside of this
+// constructor.
 func NewEnv(ctx context.Context, tb testing.TB, sandbox *fake.Sandbox, ts servertest.Connector, editorConfig fake.EditorConfig, withHooks bool) (_ *Env, cleanup func()) {
 	tb.Helper()
 
diff --git a/internal/lsp/regtest/runner.go b/internal/lsp/regtest/runner.go
index 5726f88ea0..0640e452fb 100644
--- a/internal/lsp/regtest/runner.go
+++ b/internal/lsp/regtest/runner.go
@@ -133,17 +133,27 @@ func Options(hook func(*source.Options)) RunOption {
 	})
 }
 
-func SendPID() RunOption {
+// WindowsLineEndings configures the editor to use windows line endings.
+func WindowsLineEndings() RunOption {
 	return optionSetter(func(opts *runConfig) {
-		opts.editor.SendPID = true
+		opts.editor.WindowsLineEndings = true
 	})
 }
 
-// EditorConfig is a RunOption option that configured the regtest editor.
-type EditorConfig fake.EditorConfig
+// Settings is a RunOption that sets user-provided configuration for the LSP
+// server.
+//
+// As a special case, the env setting must not be provided via Settings: use
+// EnvVars instead.
+type Settings map[string]interface{}
 
-func (c EditorConfig) set(opts *runConfig) {
-	opts.editor = fake.EditorConfig(c)
+func (s Settings) set(opts *runConfig) {
+	if opts.editor.Settings == nil {
+		opts.editor.Settings = make(map[string]interface{})
+	}
+	for k, v := range s {
+		opts.editor.Settings[k] = v
+	}
 }
 
 // WorkspaceFolders configures the workdir-relative workspace folders to send
@@ -160,6 +170,20 @@ func WorkspaceFolders(relFolders ...string) RunOption {
 	})
 }
 
+// EnvVars sets environment variables for the LSP session. When applying these
+// variables to the session, the special string $SANDBOX_WORKDIR is replaced by
+// the absolute path to the sandbox working directory.
+type EnvVars map[string]string
+
+func (e EnvVars) set(opts *runConfig) {
+	if opts.editor.Env == nil {
+		opts.editor.Env = make(map[string]string)
+	}
+	for k, v := range e {
+		opts.editor.Env[k] = v
+	}
+}
+
 // InGOPATH configures the workspace working directory to be GOPATH, rather
 // than a separate working directory for use with modules.
 func InGOPATH() RunOption {
@@ -212,13 +236,6 @@ func GOPROXY(goproxy string) RunOption {
 	})
 }
 
-// LimitWorkspaceScope sets the LimitWorkspaceScope configuration.
-func LimitWorkspaceScope() RunOption {
-	return optionSetter(func(opts *runConfig) {
-		opts.editor.LimitWorkspaceScope = true
-	})
-}
-
 type TestFunc func(t *testing.T, env *Env)
 
 // Run executes the test function in the default configured gopls execution
diff --git a/internal/lsp/regtest/wrappers.go b/internal/lsp/regtest/wrappers.go
index 96e2de9627..d8c080c0fe 100644
--- a/internal/lsp/regtest/wrappers.go
+++ b/internal/lsp/regtest/wrappers.go
@@ -7,7 +7,6 @@ package regtest
 import (
 	"encoding/json"
 	"path"
-	"testing"
 
 	"golang.org/x/tools/internal/lsp/command"
 	"golang.org/x/tools/internal/lsp/fake"
@@ -427,31 +426,10 @@ func (e *Env) CodeAction(path string, diagnostics []protocol.Diagnostic) []proto
 	return actions
 }
 
-func (e *Env) ChangeConfiguration(t *testing.T, config *fake.EditorConfig) {
-	e.Editor.Config = *config
-	if err := e.Editor.Server.DidChangeConfiguration(e.Ctx, &protocol.DidChangeConfigurationParams{
-		// gopls currently ignores the Settings field
-	}); err != nil {
-		t.Fatal(err)
-	}
-}
-
-// ChangeEnv modifies the editor environment and reconfigures the LSP client.
-// TODO: extend this to "ChangeConfiguration", once we refactor the way editor
-// configuration is defined.
-func (e *Env) ChangeEnv(overlay map[string]string) {
+// ChangeConfiguration updates the editor config, calling t.Fatal on any error.
+func (e *Env) ChangeConfiguration(newConfig fake.EditorConfig) {
 	e.T.Helper()
-	// TODO: to be correct, this should probably be synchronized, but right now
-	// configuration is only ever modified synchronously in a regtest, so this
-	// correctness can wait for the previously mentioned refactoring.
-	if e.Editor.Config.Env == nil {
-		e.Editor.Config.Env = make(map[string]string)
-	}
-	for k, v := range overlay {
-		e.Editor.Config.Env[k] = v
-	}
-	var params protocol.DidChangeConfigurationParams
-	if err := e.Editor.Server.DidChangeConfiguration(e.Ctx, &params); err != nil {
+	if err := e.Editor.ChangeConfiguration(e.Ctx, newConfig); err != nil {
 		e.T.Fatal(err)
 	}
 }