test(crit): add unit test for SearchPattern method of MemoryReader

Signed-off-by: Kouame Behouba Manasse <behouba@gmail.com>

crit/mempages_test.go

@@ -271,6 +271,81 @@ func TestGetShmemSize(t *testing.T) {
 	}
 }
 
+func TestSearchPattern(t *testing.T) {
+	pid, err := getTestImgPID()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mr, err := NewMemoryReader(testImgsDir, pid, sysPageSize)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testCases := []struct {
+		name          string
+		pattern       string
+		context       int
+		expectedError error
+		expectedCount int
+	}{
+		{
+			name:          "PATH environment variable",
+			pattern:       "PATH=",
+			expectedError: nil,
+			expectedCount: 1,
+		},
+		{
+			name:          "PATH environment variable regex",
+			pattern:       `\bPATH=([^\s]+)\b`,
+			expectedError: nil,
+			expectedCount: 1,
+		},
+		{
+			name:          "PATH environment variable regex with 10 bytes context",
+			pattern:       `\bPATH=([^\s]+)\b`,
+			context:       10,
+			expectedError: nil,
+			expectedCount: 1,
+		},
+		{
+			name:          "PATH environment variable regex with a negative context",
+			pattern:       `\bPATH=([^\s]+)\b`,
+			context:       -1,
+			expectedError: errors.New("context size cannot be negative"),
+			expectedCount: 0,
+		},
+		{
+			name:          "PATH environment variable regex with a large context",
+			pattern:       `\bPATH=([^\s]+)\b`,
+			context:       10_000,
+			expectedError: nil,
+			expectedCount: 1,
+		},
+		{
+			name:          "non existing pattern",
+			pattern:       "NON_EXISTENT_PATTERN",
+			expectedError: nil,
+			expectedCount: 0,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			results, err := mr.SearchPattern(tc.pattern, tc.context)
+			if err != nil && tc.expectedError == nil {
+				t.Errorf("Unexpected error for pattern %s: %v", tc.pattern, err)
+			} else if err == nil && tc.expectedError != nil {
+				t.Errorf("Expected error for pattern %s: %v", tc.pattern, tc.expectedError)
+			}
+
+			if len(results) != tc.expectedCount {
+				t.Errorf("Expected %d occurrences of pattern %s, but found %d", tc.expectedCount, tc.pattern, len(results))
+			}
+		})
+	}
+}
+
 // helper function to get the PID from the test-imgs directory
 func getTestImgPID() (uint32, error) {
 	psTreeImg, err := getImg(filepath.Join(testImgsDir, "pstree.img"), &pstree.PstreeEntry{})