1 files changed, 120 insertions, 0 deletions

diff --git a/internal/gotest/heuristics_test.go b/internal/gotest/heuristics_test.go
index 831262d..6597238 100644
--- a/internal/gotest/heuristics_test.go
+++ b/internal/gotest/heuristics_test.go
@@ -12,6 +12,22 @@ func TestParsePackageName(t *testing.T) {
 	}
 }
 
+func TestParsePackageName_TabAfterName(t *testing.T) {
+	// Covers the tab-trimming branch in ParsePackageName.
+	lines := []string{"package mypkg\t// tab then comment"}
+	if got := ParsePackageName(lines); got != "mypkg" {
+		t.Fatalf("got %q, want %q", got, "mypkg")
+	}
+}
+
+func TestParsePackageName_SpaceAfterName(t *testing.T) {
+	// Covers the space-trimming branch (no comment, just trailing space).
+	lines := []string{"package mypkg "}
+	if got := ParsePackageName(lines); got != "mypkg" {
+		t.Fatalf("got %q, want %q", got, "mypkg")
+	}
+}
+
 func TestFindFunctionAtLine_NoBody(t *testing.T) {
 	lines := []string{"func X(a int)", "// comment"}
 	start, end := FindFunctionAtLine(lines, 0)
@@ -20,6 +36,81 @@ func TestFindFunctionAtLine_NoBody(t *testing.T) {
 	}
 }
 
+func TestFindFunctionAtLine_EmptyLines(t *testing.T) {
+	// Covers the empty-lines early return.
+	start, end := FindFunctionAtLine([]string{}, 0)
+	if start != -1 || end != -1 {
+		t.Fatalf("expected -1,-1 for empty input, got %d,%d", start, end)
+	}
+}
+
+func TestFindFunctionAtLine_NegativeIdx(t *testing.T) {
+	// Covers the idx < 0 clamping branch.
+	lines := []string{"func Foo() {", "  return", "}"}
+	start, end := FindFunctionAtLine(lines, -5)
+	if start != 0 || end != 2 {
+		t.Fatalf("expected 0,2 got %d,%d", start, end)
+	}
+}
+
+func TestFindFunctionAtLine_IdxBeyondEnd(t *testing.T) {
+	// Covers the idx >= len(lines) clamping branch.
+	// The last line contains "func " so the backward scan finds it directly.
+	lines := []string{"package main", "", "func Last() { }"}
+	start, end := FindFunctionAtLine(lines, 100)
+	if start != 2 || end != 2 {
+		t.Fatalf("expected 2,2 got %d,%d", start, end)
+	}
+}
+
+func TestFindFunctionAtLine_ClosingBraceBeforeFunc(t *testing.T) {
+	// When scanning backward, hitting '}' before 'func ' means no enclosing function.
+	lines := []string{"func A() {", "}", "  x := 1"}
+	start, end := FindFunctionAtLine(lines, 2)
+	if start != -1 || end != -1 {
+		t.Fatalf("expected -1,-1 got %d,%d", start, end)
+	}
+}
+
+func TestFindFunctionAtLine_NormalFunction(t *testing.T) {
+	// Covers the normal path: finding a complete function with braces.
+	lines := []string{
+		"package main",
+		"",
+		"func Hello() {",
+		"  fmt.Println(\"hi\")",
+		"}",
+	}
+	start, end := FindFunctionAtLine(lines, 3)
+	if start != 2 || end != 4 {
+		t.Fatalf("expected 2,4 got %d,%d", start, end)
+	}
+}
+
+func TestFindFunctionAtLine_UnclosedBrace(t *testing.T) {
+	// Covers the branch where opening brace is seen but never closed.
+	lines := []string{"func Broken() {", "  x := 1"}
+	start, end := FindFunctionAtLine(lines, 0)
+	if start != 0 || end != -1 {
+		t.Fatalf("expected 0,-1 for unclosed brace, got %d,%d", start, end)
+	}
+}
+
+func TestFindFunctionAtLine_NestedBraces(t *testing.T) {
+	// Covers depth tracking with nested braces.
+	lines := []string{
+		"func Nested() {",
+		"  if true {",
+		"    x := 1",
+		"  }",
+		"}",
+	}
+	start, end := FindFunctionAtLine(lines, 2)
+	if start != 0 || end != 4 {
+		t.Fatalf("expected 0,4 got %d,%d", start, end)
+	}
+}
+
 func TestDeriveFuncName(t *testing.T) {
 	if got := DeriveFuncName("func Sum(a int) int { return a }"); got != "Sum" {
 		t.Fatalf("got %q", got)
@@ -29,6 +120,28 @@ func TestDeriveFuncName(t *testing.T) {
 	}
 }
 
+func TestDeriveFuncName_NotAFunc(t *testing.T) {
+	// Covers the early return when line doesn't start with "func ".
+	if got := DeriveFuncName("var x = 1"); got != "" {
+		t.Fatalf("expected empty, got %q", got)
+	}
+}
+
+func TestDeriveFuncName_MultiLine(t *testing.T) {
+	// Covers the firstLine newline-splitting branch.
+	code := "func Multi() {\n  return\n}"
+	if got := DeriveFuncName(code); got != "Multi" {
+		t.Fatalf("got %q, want %q", got, "Multi")
+	}
+}
+
+func TestDeriveFuncName_MethodReceiverNoParenAfter(t *testing.T) {
+	// Covers the case where receiver is parsed but no '(' follows the name.
+	if got := DeriveFuncName("func (t *T) "); got != "" {
+		t.Fatalf("expected empty, got %q", got)
+	}
+}
+
 func TestExportName(t *testing.T) {
 	if got := ExportName("sum"); got != "Sum" {
 		t.Fatalf("got %q", got)
@@ -37,3 +150,10 @@ func TestExportName(t *testing.T) {
 		t.Fatalf("got %q", got)
 	}
 }
+
+func TestExportName_Empty(t *testing.T) {
+	// Covers the empty-string early return.
+	if got := ExportName(""); got != "" {
+		t.Fatalf("expected empty, got %q", got)
+	}
+}