Turn symbol_inject into a reusable package

Bug: 31559095
Test: m blueprint_tools
Change-Id: I0f7a9f14111af26d753db547c6de313a7079658a
diff --git a/symbol_inject/macho_test.go b/symbol_inject/macho_test.go
new file mode 100644
index 0000000..50df131
--- /dev/null
+++ b/symbol_inject/macho_test.go
@@ -0,0 +1,64 @@
+// Copyright 2018 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package symbol_inject
+
+import (
+	"debug/macho"
+	"strconv"
+	"testing"
+)
+
+func TestMachoSymbolTable(t *testing.T) {
+	testCases := []struct {
+		file         *macho.File
+		symbol       string
+		offset, size uint64
+	}{
+		{
+			file:   machoSymbolTable1,
+			symbol: "soong_build_number",
+			offset: 0x1020,
+			size:   128,
+		},
+		{
+			file:   machoSymbolTable2,
+			symbol: "symbol1",
+			offset: 0x1020,
+			size:   128,
+		},
+		{
+			file:   machoSymbolTable2,
+			symbol: "symbol2",
+			offset: 0x10a0,
+			size:   128,
+		},
+	}
+
+	for i, testCase := range testCases {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			file, err := extractMachoSymbols(testCase.file)
+			if err != nil {
+				t.Error(err.Error())
+			}
+			offset, size, err := findSymbol(file, testCase.symbol)
+			if err != nil {
+				t.Error(err.Error())
+			}
+			if offset != testCase.offset || size != testCase.size {
+				t.Errorf("expected %x:%x, got %x:%x", testCase.offset, testCase.size, offset, size)
+			}
+		})
+	}
+}