gopls/internal/test/misc: Fix two flaky tests

In gopls the module index is maintained with background
go routines. Tests that depend on the module index will be flaky
if the background work doesn't finish in time. Instead, construct
the module index deterministically.

Fixes: golang/go#77552
Fixes: golang/go#77894
Change-Id: I9f458d02e044d5d708a49faeae41c7554d0e1498
Reviewed-on: https://go-review.googlesource.com/c/tools/+/796440
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Madeline Kalil <mkalil@google.com>

gopls/internal/test/integration/misc/imports_test.go

diff --git a/gopls/internal/test/integration/misc/imports_test.go b/gopls/internal/test/integration/misc/imports_test.go
index 304531b..409fb18 100644
--- a/gopls/internal/test/integration/misc/imports_test.go
+++ b/gopls/internal/test/integration/misc/imports_test.go
@@ -244,6 +244,13 @@
 		WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {})
 	})
 
+	// according to https://github.com/golang/go/issues/77894
+	// this test is flaky. Create the index deterministically
+	// rather than hoping that a background go routine completes in time.
+	if _, err := modindex.Update(modcache); err != nil {
+		t.Fatal(err)
+	}
+
 	WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {
 		// Expect y is undefined.
 		env.OpenFile("main.go")
@@ -255,44 +262,6 @@
 
 		// Apply suggested fix via OrganizeImports.
 		env.SaveBuffer("main.go") // => OrganizeImports
-		if true {
-			// according to https://github.com/golang/go/issues/77894
-			// this test is flaky. Print some possibly helpful diagnostic
-			// information.
-			ix, err := modindex.Read(modcache)
-			if err != nil {
-				t.Logf("could not read modcache index: %v", err)
-			} else if len(ix.Entries) != 2 {
-				t.Logf("%d modcache entries", len(ix.Entries))
-				if len(ix.Entries) == 0 {
-					fis, err := os.ReadDir(modcache)
-					if err != nil {
-						t.Logf("could not read modcache dir: %v", err)
-					}
-					t.Logf("%d modcache files", len(fis))
-				}
-			}
-			// because this test is flaky, replace the simple check with a detailed one
-			// env.AfterChange(NoDiagnostics(ForFile("main.go")))
-			diags := make(map[string]*protocol.PublishDiagnosticsParams)
-			env.AfterChange(ReadAllDiagnostics(&diags))
-			dump := false
-			for k, v := range diags {
-				if len(v.Diagnostics) != 0 {
-					t.Errorf("Unexpected diagnostics for %s: %#v", k, v)
-					dump = true
-				}
-			}
-			if dump {
-				/* the correct result is
-					0: example.com/x, example.com@v1.2.3/x, ["X C"]
-				   	1: example.com/y, example.com@v1.2.3/y, ["Y C"]
-				*/
-				for i, e := range ix.Entries {
-					t.Logf("%d: %s, %s, %q", i, e.ImportPath, e.Dir, e.Names)
-				}
-			}
-		}
 
 		// Verify that y.Y is defined within the module cache.
 		loc := env.FirstDefinition(env.RegexpSearch("main.go", `y.(Y)`))
@@ -347,6 +316,9 @@
 			t.Logf("wrote %s:%d", fname, len(v))
 		}
 	}
+	// golang/go#77552 finds this test flaky, so create the index explicitly
+	// rather than hoping a background go routine finishes in time
+	modindex.Update(modcache)
 	WithOptions(
 		EnvVars{"GOMODCACHE": modcache},
 		WriteGoSum("."),
@@ -358,15 +330,6 @@
 		out := env.BufferText("main.go")
 		if !strings.Contains(out, "xurls/v2") {
 			t.Errorf("did not get v2 in %q", out)
-			// golang/go#77552 finds this test flaky, so print out more
-			ix, err := modindex.Read(modcache)
-			if err != nil {
-				t.Fatal(err)
-			}
-			t.Logf("%d entries", len(ix.Entries))
-			for i, e := range ix.Entries {
-				t.Logf("%d: %s, %s, %d", i, e.ImportPath, e.Dir, len(e.Names))
-			}
 		}
 	})
 }